refactor performance counter code

This commit performs some general refactoring, including...
- avoid manually duplicating the event list;
- rework the 'is important' event flag;
- remove the new packages (Cyotek.Collections can be replaced with built-in types, and System.ValueTuple won't work in the Mono version used on Linux/Mac);
- improve performance;
- minor cleanup.

16 files changed, 383 insertions, 445 deletions

diff --git a/src/SMAPI/Constants.cs b/src/SMAPI/Constants.cs
index 76cb6f89..67c7b576 100644
--- a/src/SMAPI/Constants.cs
+++ b/src/SMAPI/Constants.cs
@@ -55,7 +55,7 @@ namespace StardewModdingAPI
         /// <summary>The URL of the SMAPI home page.</summary>
         internal const string HomePageUrl = "https://smapi.io";
 
-        /// <summary>The URL of the SMAPI home page.</summary>
+        /// <summary>The default performance counter name for unknown event handlers.</summary>
         internal const string GamePerformanceCounterName = "<StardewValley>";
 
         /// <summary>The absolute path to the folder containing SMAPI's internal files.</summary>
@@ -103,6 +103,7 @@ namespace StardewModdingAPI
         /// <summary>The language code for non-translated mod assets.</summary>
         internal static LocalizedContentManager.LanguageCode DefaultLanguage { get; } = LocalizedContentManager.LanguageCode.en;
 
+
         /*********
         ** Internal methods
         *********/
diff --git a/src/SMAPI/Framework/Events/EventManager.cs b/src/SMAPI/Framework/Events/EventManager.cs
index 19a4dff8..50dcc9ef 100644
--- a/src/SMAPI/Framework/Events/EventManager.cs
+++ b/src/SMAPI/Framework/Events/EventManager.cs
@@ -1,4 +1,6 @@
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using System.Reflection;
 using StardewModdingAPI.Events;
 using StardewModdingAPI.Framework.PerformanceCounter;
 
@@ -174,29 +176,32 @@ namespace StardewModdingAPI.Framework.Events
         /// <summary>Construct an instance.</summary>
         /// <param name="monitor">Writes messages to the log.</param>
         /// <param name="modRegistry">The mod registry with which to identify mods.</param>
-        /// <param name="performanceCounterManager">The performance counter manager.</param>
-        public EventManager(IMonitor monitor, ModRegistry modRegistry, PerformanceCounterManager performanceCounterManager)
+        /// <param name="performanceMonitor">Tracks performance metrics.</param>
+        public EventManager(IMonitor monitor, ModRegistry modRegistry, PerformanceMonitor performanceMonitor)
         {
             // create shortcut initializers
-            ManagedEvent<TEventArgs> ManageEventOf<TEventArgs>(string typeName, string eventName) => new ManagedEvent<TEventArgs>($"{typeName}.{eventName}", monitor, modRegistry, performanceCounterManager);
+            ManagedEvent<TEventArgs> ManageEventOf<TEventArgs>(string typeName, string eventName, bool isPerformanceCritical = false)
+            {
+                return new ManagedEvent<TEventArgs>($"{typeName}.{eventName}", monitor, modRegistry, performanceMonitor, isPerformanceCritical);
+            }
 
             // init events (new)
             this.MenuChanged = ManageEventOf<MenuChangedEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.MenuChanged));
-            this.Rendering = ManageEventOf<RenderingEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.Rendering));
-            this.Rendered = ManageEventOf<RenderedEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.Rendered));
-            this.RenderingWorld = ManageEventOf<RenderingWorldEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderingWorld));
-            this.RenderedWorld = ManageEventOf<RenderedWorldEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderedWorld));
-            this.RenderingActiveMenu = ManageEventOf<RenderingActiveMenuEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderingActiveMenu));
-            this.RenderedActiveMenu = ManageEventOf<RenderedActiveMenuEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderedActiveMenu));
-            this.RenderingHud = ManageEventOf<RenderingHudEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderingHud));
-            this.RenderedHud = ManageEventOf<RenderedHudEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderedHud));
+            this.Rendering = ManageEventOf<RenderingEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.Rendering), isPerformanceCritical: true);
+            this.Rendered = ManageEventOf<RenderedEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.Rendered), isPerformanceCritical: true);
+            this.RenderingWorld = ManageEventOf<RenderingWorldEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderingWorld), isPerformanceCritical: true);
+            this.RenderedWorld = ManageEventOf<RenderedWorldEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderedWorld), isPerformanceCritical: true);
+            this.RenderingActiveMenu = ManageEventOf<RenderingActiveMenuEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderingActiveMenu), isPerformanceCritical: true);
+            this.RenderedActiveMenu = ManageEventOf<RenderedActiveMenuEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderedActiveMenu), isPerformanceCritical: true);
+            this.RenderingHud = ManageEventOf<RenderingHudEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderingHud), isPerformanceCritical: true);
+            this.RenderedHud = ManageEventOf<RenderedHudEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.RenderedHud), isPerformanceCritical: true);
             this.WindowResized = ManageEventOf<WindowResizedEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.WindowResized));
 
             this.GameLaunched = ManageEventOf<GameLaunchedEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.GameLaunched));
-            this.UpdateTicking = ManageEventOf<UpdateTickingEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.UpdateTicking));
-            this.UpdateTicked = ManageEventOf<UpdateTickedEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.UpdateTicked));
-            this.OneSecondUpdateTicking = ManageEventOf<OneSecondUpdateTickingEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.OneSecondUpdateTicking));
-            this.OneSecondUpdateTicked = ManageEventOf<OneSecondUpdateTickedEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.OneSecondUpdateTicked));
+            this.UpdateTicking = ManageEventOf<UpdateTickingEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.UpdateTicking), isPerformanceCritical: true);
+            this.UpdateTicked = ManageEventOf<UpdateTickedEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.UpdateTicked), isPerformanceCritical: true);
+            this.OneSecondUpdateTicking = ManageEventOf<OneSecondUpdateTickingEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.OneSecondUpdateTicking), isPerformanceCritical: true);
+            this.OneSecondUpdateTicked = ManageEventOf<OneSecondUpdateTickedEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.OneSecondUpdateTicked), isPerformanceCritical: true);
             this.SaveCreating = ManageEventOf<SaveCreatingEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.SaveCreating));
             this.SaveCreated = ManageEventOf<SaveCreatedEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.SaveCreated));
             this.Saving = ManageEventOf<SavingEventArgs>(nameof(IModEvents.GameLoop), nameof(IGameLoopEvents.Saving));
@@ -209,7 +214,7 @@ namespace StardewModdingAPI.Framework.Events
 
             this.ButtonPressed = ManageEventOf<ButtonPressedEventArgs>(nameof(IModEvents.Input), nameof(IInputEvents.ButtonPressed));
             this.ButtonReleased = ManageEventOf<ButtonReleasedEventArgs>(nameof(IModEvents.Input), nameof(IInputEvents.ButtonReleased));
-            this.CursorMoved = ManageEventOf<CursorMovedEventArgs>(nameof(IModEvents.Input), nameof(IInputEvents.CursorMoved));
+            this.CursorMoved = ManageEventOf<CursorMovedEventArgs>(nameof(IModEvents.Input), nameof(IInputEvents.CursorMoved), isPerformanceCritical: true);
             this.MouseWheelScrolled = ManageEventOf<MouseWheelScrolledEventArgs>(nameof(IModEvents.Input), nameof(IInputEvents.MouseWheelScrolled));
 
             this.PeerContextReceived = ManageEventOf<PeerContextReceivedEventArgs>(nameof(IModEvents.Multiplayer), nameof(IMultiplayerEvents.PeerContextReceived));
@@ -230,8 +235,15 @@ namespace StardewModdingAPI.Framework.Events
             this.TerrainFeatureListChanged = ManageEventOf<TerrainFeatureListChangedEventArgs>(nameof(IModEvents.World), nameof(IWorldEvents.TerrainFeatureListChanged));
 
             this.LoadStageChanged = ManageEventOf<LoadStageChangedEventArgs>(nameof(IModEvents.Specialized), nameof(ISpecializedEvents.LoadStageChanged));
-            this.UnvalidatedUpdateTicking = ManageEventOf<UnvalidatedUpdateTickingEventArgs>(nameof(IModEvents.Specialized), nameof(ISpecializedEvents.UnvalidatedUpdateTicking));
-            this.UnvalidatedUpdateTicked = ManageEventOf<UnvalidatedUpdateTickedEventArgs>(nameof(IModEvents.Specialized), nameof(ISpecializedEvents.UnvalidatedUpdateTicked));
+            this.UnvalidatedUpdateTicking = ManageEventOf<UnvalidatedUpdateTickingEventArgs>(nameof(IModEvents.Specialized), nameof(ISpecializedEvents.UnvalidatedUpdateTicking), isPerformanceCritical: true);
+            this.UnvalidatedUpdateTicked = ManageEventOf<UnvalidatedUpdateTickedEventArgs>(nameof(IModEvents.Specialized), nameof(ISpecializedEvents.UnvalidatedUpdateTicked), isPerformanceCritical: true);
+        }
+
+        /// <summary>Get all managed events.</summary>
+        public IEnumerable<IManagedEvent> GetAllEvents()
+        {
+            foreach (FieldInfo field in this.GetType().GetFields())
+                yield return (IManagedEvent)field.GetValue(this);
         }
     }
 }
diff --git a/src/SMAPI/Framework/Events/IManagedEvent.cs b/src/SMAPI/Framework/Events/IManagedEvent.cs
index 04476866..e4e3ca08 100644
--- a/src/SMAPI/Framework/Events/IManagedEvent.cs
+++ b/src/SMAPI/Framework/Events/IManagedEvent.cs
@@ -1,7 +1,15 @@
 namespace StardewModdingAPI.Framework.Events
 {
+    /// <summary>Metadata for an event raised by SMAPI.</summary>
     internal interface IManagedEvent
     {
-        string GetName();
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A human-readable name for the event.</summary>
+        string EventName { get; }
+
+        /// <summary>Whether the event is typically called at least once per second.</summary>
+        bool IsPerformanceCritical { get; }
     }
 }
diff --git a/src/SMAPI/Framework/Events/ManagedEvent.cs b/src/SMAPI/Framework/Events/ManagedEvent.cs
index dfdd7449..60e5c599 100644
--- a/src/SMAPI/Framework/Events/ManagedEvent.cs
+++ b/src/SMAPI/Framework/Events/ManagedEvent.cs
@@ -1,13 +1,13 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using PerformanceCounterManager = StardewModdingAPI.Framework.PerformanceCounter.PerformanceCounterManager;
+using StardewModdingAPI.Framework.PerformanceCounter;
 
 namespace StardewModdingAPI.Framework.Events
 {
     /// <summary>An event wrapper which intercepts and logs errors in handler code.</summary>
     /// <typeparam name="TEventArgs">The event arguments type.</typeparam>
-    internal class ManagedEvent<TEventArgs>: IManagedEvent
+    internal class ManagedEvent<TEventArgs> : IManagedEvent
     {
         /*********
         ** Fields
@@ -15,9 +15,6 @@ namespace StardewModdingAPI.Framework.Events
         /// <summary>The underlying event.</summary>
         private event EventHandler<TEventArgs> Event;
 
-        /// <summary>A human-readable name for the event.</summary>
-        private readonly string EventName;
-
         /// <summary>Writes messages to the log.</summary>
         private readonly IMonitor Monitor;
 
@@ -30,8 +27,19 @@ namespace StardewModdingAPI.Framework.Events
         /// <summary>The cached invocation list.</summary>
         private EventHandler<TEventArgs>[] CachedInvocationList;
 
-        /// <summary>The performance counter manager.</summary>
-        private readonly PerformanceCounterManager PerformanceCounterManager;
+        /// <summary>Tracks performance metrics.</summary>
+        private readonly PerformanceMonitor PerformanceMonitor;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A human-readable name for the event.</summary>
+        public string EventName { get; }
+
+        /// <summary>Whether the event is typically called at least once per second.</summary>
+        public bool IsPerformanceCritical { get; }
+
 
         /*********
         ** Public methods
@@ -40,19 +48,15 @@ namespace StardewModdingAPI.Framework.Events
         /// <param name="eventName">A human-readable name for the event.</param>
         /// <param name="monitor">Writes messages to the log.</param>
         /// <param name="modRegistry">The mod registry with which to identify mods.</param>
-        /// <param name="performanceCounterManager">The performance counter manager</param>
-        public ManagedEvent(string eventName, IMonitor monitor, ModRegistry modRegistry, PerformanceCounterManager performanceCounterManager)
+        /// <param name="performanceMonitor">Tracks performance metrics.</param>
+        /// <param name="isPerformanceCritical">Whether the event is typically called at least once per second.</param>
+        public ManagedEvent(string eventName, IMonitor monitor, ModRegistry modRegistry, PerformanceMonitor performanceMonitor, bool isPerformanceCritical = false)
         {
             this.EventName = eventName;
             this.Monitor = monitor;
             this.ModRegistry = modRegistry;
-            this.PerformanceCounterManager = performanceCounterManager;
-        }
-
-        /// <summary>Gets the event name.</summary>
-        public string GetName()
-        {
-            return this.EventName;
+            this.PerformanceMonitor = performanceMonitor;
+            this.IsPerformanceCritical = isPerformanceCritical;
         }
 
         /// <summary>Get whether anything is listening to the event.</summary>
@@ -93,22 +97,20 @@ namespace StardewModdingAPI.Framework.Events
                 return;
 
 
-            this.PerformanceCounterManager.BeginTrackInvocation(this.EventName);
-
-            foreach (EventHandler<TEventArgs> handler in this.CachedInvocationList)
+            this.PerformanceMonitor.Track(this.EventName, () =>
             {
-                try
-                {
-                    this.PerformanceCounterManager.Track(this.EventName, this.GetModNameForPerformanceCounters(handler),
-                        () => handler.Invoke(null, args));
-                }
-                catch (Exception ex)
+                foreach (EventHandler<TEventArgs> handler in this.CachedInvocationList)
                 {
-                    this.LogError(handler, ex);
+                    try
+                    {
+                        this.PerformanceMonitor.Track(this.EventName, this.GetModNameForPerformanceCounters(handler), () => handler.Invoke(null, args));
+                    }
+                    catch (Exception ex)
+                    {
+                        this.LogError(handler, ex);
+                    }
                 }
-            }
-
-            this.PerformanceCounterManager.EndTrackInvocation(this.EventName);
+            });
         }
 
         /// <summary>Raise the event and notify all handlers.</summary>
@@ -139,18 +141,17 @@ namespace StardewModdingAPI.Framework.Events
         /*********
         ** Private methods
         *********/
-
+        /// <summary>Get the mod name for a given event handler to display in performance monitoring reports.</summary>
+        /// <param name="handler">The event handler.</param>
         private string GetModNameForPerformanceCounters(EventHandler<TEventArgs> handler)
         {
             IModMetadata mod = this.GetSourceMod(handler);
-
             if (mod == null)
-            {
                 return Constants.GamePerformanceCounterName;
-            }
-
-            return mod.HasManifest() ? mod.Manifest.UniqueID : mod.DisplayName;
 
+            return mod.HasManifest()
+                ? mod.Manifest.UniqueID
+                : mod.DisplayName;
         }
 
         /// <summary>Track an event handler.</summary>
diff --git a/src/SMAPI/Framework/PerformanceCounter/AlertContext.cs b/src/SMAPI/Framework/PerformanceCounter/AlertContext.cs
index 63f0a5ed..76c472e1 100644
--- a/src/SMAPI/Framework/PerformanceCounter/AlertContext.cs
+++ b/src/SMAPI/Framework/PerformanceCounter/AlertContext.cs
@@ -3,13 +3,20 @@ namespace StardewModdingAPI.Framework.PerformanceCounter
     /// <summary>The context for an alert.</summary>
     internal struct AlertContext
     {
+        /*********
+        ** Accessors
+        *********/
         /// <summary>The source which triggered the alert.</summary>
-        public readonly string Source;
+        public string Source { get; }
 
         /// <summary>The elapsed milliseconds.</summary>
-        public readonly double Elapsed;
+        public double Elapsed { get; }
 
-        /// <summary>Creates a new alert context.</summary>
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
         /// <param name="source">The source which triggered the alert.</param>
         /// <param name="elapsed">The elapsed milliseconds.</param>
         public AlertContext(string source, double elapsed)
@@ -18,6 +25,7 @@ namespace StardewModdingAPI.Framework.PerformanceCounter
             this.Elapsed = elapsed;
         }
 
+        /// <summary>Get a human-readable text form of this instance.</summary>
         public override string ToString()
         {
             return $"{this.Source}: {this.Elapsed:F2}ms";
diff --git a/src/SMAPI/Framework/PerformanceCounter/AlertEntry.cs b/src/SMAPI/Framework/PerformanceCounter/AlertEntry.cs
index b87d8642..494f34a9 100644
--- a/src/SMAPI/Framework/PerformanceCounter/AlertEntry.cs
+++ b/src/SMAPI/Framework/PerformanceCounter/AlertEntry.cs
@@ -1,28 +1,33 @@
-using System.Collections.Generic;
-
 namespace StardewModdingAPI.Framework.PerformanceCounter
 {
     /// <summary>A single alert entry.</summary>
     internal struct AlertEntry
     {
+        /*********
+        ** Accessors
+        *********/
         /// <summary>The collection in which the alert occurred.</summary>
-        public readonly PerformanceCounterCollection Collection;
+        public PerformanceCounterCollection Collection { get; }
 
         /// <summary>The actual execution time in milliseconds.</summary>
-        public readonly double ExecutionTimeMilliseconds;
+        public double ExecutionTimeMilliseconds { get; }
+
+        /// <summary>The configured alert threshold in milliseconds.</summary>
+        public double ThresholdMilliseconds { get; }
 
-        /// <summary>The configured alert threshold. </summary>
-        public readonly double ThresholdMilliseconds;
+        /// <summary>The sources involved in exceeding the threshold.</summary>
+        public AlertContext[] Context { get; }
 
-        /// <summary>The context list, which records all sources involved in exceeding the threshold.</summary>
-        public readonly List<AlertContext> Context;
 
-        /// <summary>Creates a new alert entry.</summary>
-        /// <param name="collection">The source collection in which the alert occurred.</param>
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="collection">The collection in which the alert occurred.</param>
         /// <param name="executionTimeMilliseconds">The actual execution time in milliseconds.</param>
-        /// <param name="thresholdMilliseconds">The configured threshold in milliseconds.</param>
-        /// <param name="context">A list of AlertContext to record which sources were involved</param>
-        public AlertEntry(PerformanceCounterCollection collection, double executionTimeMilliseconds, double thresholdMilliseconds, List<AlertContext> context)
+        /// <param name="thresholdMilliseconds">The configured alert threshold in milliseconds.</param>
+        /// <param name="context">The sources involved in exceeding the threshold.</param>
+        public AlertEntry(PerformanceCounterCollection collection, double executionTimeMilliseconds, double thresholdMilliseconds, AlertContext[] context)
         {
             this.Collection = collection;
             this.ExecutionTimeMilliseconds = executionTimeMilliseconds;
diff --git a/src/SMAPI/Framework/PerformanceCounter/EventPerformanceCounterCollection.cs b/src/SMAPI/Framework/PerformanceCounter/EventPerformanceCounterCollection.cs
deleted file mode 100644
index 4690c512..00000000
--- a/src/SMAPI/Framework/PerformanceCounter/EventPerformanceCounterCollection.cs
+++ /dev/null
@@ -1,16 +0,0 @@
-using StardewModdingAPI.Framework.Events;
-
-namespace StardewModdingAPI.Framework.PerformanceCounter
-{
-    /// <summary>Represents a performance counter collection specific to game events.</summary>
-    internal class EventPerformanceCounterCollection: PerformanceCounterCollection
-    {
-        /// <summary>Creates a new event performance counter collection.</summary>
-        /// <param name="manager">The performance counter manager.</param>
-        /// <param name="event">The ManagedEvent.</param>
-        /// <param name="isImportant">If the event is flagged as important.</param>
-        public EventPerformanceCounterCollection(PerformanceCounterManager manager, IManagedEvent @event, bool isImportant) : base(manager, @event.GetName(), isImportant)
-        {
-        }
-    }
-}
diff --git a/src/SMAPI/Framework/PerformanceCounter/PeakEntry.cs b/src/SMAPI/Framework/PerformanceCounter/PeakEntry.cs
index 95dc11f4..abb29541 100644
--- a/src/SMAPI/Framework/PerformanceCounter/PeakEntry.cs
+++ b/src/SMAPI/Framework/PerformanceCounter/PeakEntry.cs
@@ -1,20 +1,31 @@
 using System;
-using System.Collections.Generic;
 
 namespace StardewModdingAPI.Framework.PerformanceCounter
 {
+    /// <summary>A peak invocation time.</summary>
     internal struct PeakEntry
     {
+        /*********
+        ** Accessors
+        *********/
         /// <summary>The actual execution time in milliseconds.</summary>
-        public readonly double ExecutionTimeMilliseconds;
+        public double ExecutionTimeMilliseconds { get; }
 
-        /// <summary>The DateTime when the entry occured.</summary>
-        public DateTime EventTime;
+        /// <summary>When the entry occurred.</summary>
+        public DateTime EventTime { get; }
 
-        /// <summary>The context list, which records all sources involved in exceeding the threshold.</summary>
-        public readonly List<AlertContext> Context;
+        /// <summary>The sources involved in exceeding the threshold.</summary>
+        public AlertContext[] Context { get; }
 
-        public PeakEntry(double executionTimeMilliseconds, DateTime eventTime, List<AlertContext> context)
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="executionTimeMilliseconds">The actual execution time in milliseconds.</param>
+        /// <param name="eventTime">When the entry occurred.</param>
+        /// <param name="context">The sources involved in exceeding the threshold.</param>
+        public PeakEntry(double executionTimeMilliseconds, DateTime eventTime, AlertContext[] context)
         {
             this.ExecutionTimeMilliseconds = executionTimeMilliseconds;
             this.EventTime = eventTime;
diff --git a/src/SMAPI/Framework/PerformanceCounter/PerformanceCounter.cs b/src/SMAPI/Framework/PerformanceCounter/PerformanceCounter.cs
index e9dfcb14..0fb6482d 100644
--- a/src/SMAPI/Framework/PerformanceCounter/PerformanceCounter.cs
+++ b/src/SMAPI/Framework/PerformanceCounter/PerformanceCounter.cs
@@ -1,23 +1,32 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
-using Cyotek.Collections.Generic;
+using Harmony;
 
 namespace StardewModdingAPI.Framework.PerformanceCounter
 {
+    /// <summary>Tracks metadata about a particular code event.</summary>
     internal class PerformanceCounter
     {
+        /*********
+        ** Fields
+        *********/
         /// <summary>The size of the ring buffer.</summary>
-        private const int MAX_ENTRIES = 16384;
+        private readonly int MaxEntries = 16384;
 
         /// <summary>The collection to which this performance counter belongs.</summary>
         private readonly PerformanceCounterCollection ParentCollection;
 
-        /// <summary>The circular buffer which stores all performance counter entries</summary>
-        private readonly CircularBuffer<PerformanceCounterEntry> _counter;
+        /// <summary>The performance counter entries.</summary>
+        private readonly Stack<PerformanceCounterEntry> Entries;
 
-        /// <summary>The peak execution time</summary>
+        /// <summary>The entry with the highest execution time.</summary>
         private PerformanceCounterEntry? PeakPerformanceCounterEntry;
 
+
+        /*********
+        ** Accessors
+        *********/
         /// <summary>The name of the source.</summary>
         public string Source { get; }
 
@@ -27,118 +36,90 @@ namespace StardewModdingAPI.Framework.PerformanceCounter
         /// <summary>If alerting is enabled or not</summary>
         public bool EnableAlerts { get; set; }
 
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="parentCollection">The collection to which this performance counter belongs.</param>
+        /// <param name="source">The name of the source.</param>
         public PerformanceCounter(PerformanceCounterCollection parentCollection, string source)
         {
             this.ParentCollection = parentCollection;
             this.Source = source;
-            this._counter = new CircularBuffer<PerformanceCounterEntry>(PerformanceCounter.MAX_ENTRIES);
+            this.Entries = new Stack<PerformanceCounterEntry>(this.MaxEntries);
         }
 
-        /// <summary>Adds a new performance counter entry to the list. Updates the peak entry and adds an alert if
-        /// monitoring is enabled and the execution time exceeds the threshold.</summary>
+        /// <summary>Add a performance counter entry to the list, update monitoring, and raise alerts if needed.</summary>
         /// <param name="entry">The entry to add.</param>
         public void Add(PerformanceCounterEntry entry)
         {
-            this._counter.Put(entry);
-
-            if (this.EnableAlerts && entry.ElapsedMilliseconds > this.AlertThresholdMilliseconds)
-                this.ParentCollection.AddAlert(entry.ElapsedMilliseconds, this.AlertThresholdMilliseconds,
-                    new AlertContext(this.Source, entry.ElapsedMilliseconds));
+            // add entry
+            if (this.Entries.Count > this.MaxEntries)
+                this.Entries.Pop();
+            this.Entries.Add(entry);
 
-            if (this.PeakPerformanceCounterEntry == null)
+            // update metrics
+            if (this.PeakPerformanceCounterEntry == null || entry.ElapsedMilliseconds > this.PeakPerformanceCounterEntry.Value.ElapsedMilliseconds)
                 this.PeakPerformanceCounterEntry = entry;
-            else
-            {
-                if (entry.ElapsedMilliseconds > this.PeakPerformanceCounterEntry.Value.ElapsedMilliseconds)
-                    this.PeakPerformanceCounterEntry = entry;
-            }
+
+            // raise alert
+            if (this.EnableAlerts && entry.ElapsedMilliseconds > this.AlertThresholdMilliseconds)
+                this.ParentCollection.AddAlert(entry.ElapsedMilliseconds, this.AlertThresholdMilliseconds, new AlertContext(this.Source, entry.ElapsedMilliseconds));
         }
 
-        /// <summary>Clears all performance counter entries and resets the peak entry.</summary>
+        /// <summary>Clear all performance counter entries and monitoring.</summary>
         public void Reset()
         {
-            this._counter.Clear();
+            this.Entries.Clear();
             this.PeakPerformanceCounterEntry = null;
         }
 
-        /// <summary>Returns the peak entry.</summary>
-        /// <returns>The peak entry.</returns>
+        /// <summary>Get the peak entry.</summary>
         public PerformanceCounterEntry? GetPeak()
         {
             return this.PeakPerformanceCounterEntry;
         }
 
-        /// <summary>Returns the peak entry.</summary>
-        /// <returns>The peak entry.</returns>
-        public PerformanceCounterEntry? GetPeak(TimeSpan range, DateTime? relativeTo = null)
+        /// <summary>Get the entry with the highest execution time.</summary>
+        /// <param name="range">The time range to search.</param>
+        /// <param name="endTime">The end time for the <paramref name="range"/>, or null for the current time.</param>
+        public PerformanceCounterEntry? GetPeak(TimeSpan range, DateTime? endTime = null)
         {
-            if (this._counter.IsEmpty)
-                return null;
-
-            if (relativeTo == null)
-                relativeTo = DateTime.UtcNow;
-
-            DateTime start = relativeTo.Value.Subtract(range);
-
-            var entries = this._counter.Where(x => (x.EventTime >= start) && (x.EventTime <= relativeTo)).ToList();
-
-            if (!entries.Any())
-                return null;
+            endTime ??= DateTime.UtcNow;
+            DateTime startTime = endTime.Value.Subtract(range);
 
-            return entries.OrderByDescending(x => x.ElapsedMilliseconds).First();
+            return this.Entries
+                .Where(entry => entry.EventTime >= startTime && entry.EventTime <= endTime)
+                .OrderByDescending(x => x.ElapsedMilliseconds)
+                .FirstOrDefault();
         }
 
-        /// <summary>Resets the peak entry.</summary>
-        public void ResetPeak()
-        {
-            this.PeakPerformanceCounterEntry = null;
-        }
-
-        /// <summary>Returns the last entry added to the list.</summary>
-        /// <returns>The last entry</returns>
+        /// <summary>Get the last entry added to the list.</summary>
         public PerformanceCounterEntry? GetLastEntry()
         {
-            if (this._counter.IsEmpty)
+            if (this.Entries.Count == 0)
                 return null;
 
-            return this._counter.PeekLast();
+            return this.Entries.Peek();
         }
 
-        /// <summary>Returns the average execution time of all entries.</summary>
-        /// <returns>The average execution time in milliseconds.</returns>
-        public double GetAverage()
+        /// <summary>Get the average over a given time span.</summary>
+        /// <param name="range">The time range to search.</param>
+        /// <param name="endTime">The end time for the <paramref name="range"/>, or null for the current time.</param>
+        public double GetAverage(TimeSpan range, DateTime? endTime = null)
         {
-            if (this._counter.IsEmpty)
-                return 0;
-
-            return this._counter.Average(p => p.ElapsedMilliseconds);
-        }
-
-        /// <summary>Returns the average over a given time span.</summary>
-        /// <param name="range">The time range to retrieve.</param>
-        /// <param name="relativeTo">The DateTime from which to start the average. Defaults to DateTime.UtcNow if null</param>
-        /// <returns>The average execution time in milliseconds.</returns>
-        /// <remarks>
-        /// The relativeTo parameter specifies from which point in time the range is subtracted. Example:
-        /// If DateTime is set to 60 seconds ago, and the range is set to 60 seconds, the method would return
-        /// the average between all entries between 120s ago and 60s ago.
-        /// </remarks>
-        public double GetAverage(TimeSpan range, DateTime? relativeTo = null)
-        {
-            if (this._counter.IsEmpty)
-                return 0;
-
-            if (relativeTo == null)
-                relativeTo = DateTime.UtcNow;
-
-            DateTime start = relativeTo.Value.Subtract(range);
-
-            var entries = this._counter.Where(x => (x.EventTime >= start) && (x.EventTime <= relativeTo)).ToList();
+            endTime ??= DateTime.UtcNow;
+            DateTime startTime = endTime.Value.Subtract(range);
 
-            if (!entries.Any())
-                return 0;
+            double[] entries = this.Entries
+                .Where(entry => entry.EventTime >= startTime && entry.EventTime <= endTime)
+                .Select(p => p.ElapsedMilliseconds)
+                .ToArray();
 
-            return entries.Average(x => x.ElapsedMilliseconds);
+            return entries.Length > 0
+                ? entries.Average()
+                : 0;
         }
     }
 }
diff --git a/src/SMAPI/Framework/PerformanceCounter/PerformanceCounterCollection.cs b/src/SMAPI/Framework/PerformanceCounter/PerformanceCounterCollection.cs
index f469eceb..bd13a36e 100644
--- a/src/SMAPI/Framework/PerformanceCounter/PerformanceCounterCollection.cs
+++ b/src/SMAPI/Framework/PerformanceCounter/PerformanceCounterCollection.cs
@@ -2,153 +2,129 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using Cyotek.Collections.Generic;