Apply optimizations in Avalonia iOS (#20969)

* Apply optimizations on Avalonia iOS

* Updated benchmarks

* More changes

* Removed iOS Benchmarks project

src/iOS/Avalonia.iOS/DispatcherImpl.cs

@@ -22,7 +22,8 @@ internal class DispatcherImpl : IDispatcherImplWithExplicitBackgroundProcessing
     private readonly IntPtr _mainLoop;
     private readonly IntPtr _mainQueue;
     private Thread? _loopThread;
-    private bool _backgroundProcessingRequested, _signaled;
+    private bool _backgroundProcessingRequested;
+    private int _signaled;
 
     private unsafe DispatcherImpl()
     {
@@ -60,15 +61,12 @@ internal class DispatcherImpl : IDispatcherImplWithExplicitBackgroundProcessing
 
     public unsafe void Signal()
     {
-        lock (_sync)
+        if (Interlocked.CompareExchange(ref _signaled, 1, 0) != 0)
         {
-            if (_signaled)
-                return;
-            _signaled = true;
-
-            Interop.dispatch_async_f(_mainQueue, IntPtr.Zero, &CheckSignaled);
-            Interop.CFRunLoopWakeUp(_mainLoop);
+            return;
         }
+        Interop.dispatch_async_f(_mainQueue, IntPtr.Zero, &CheckSignaled);
+        Interop.CFRunLoopWakeUp(_mainLoop);
     }
 
     public void UpdateTimer(long? dueTimeInMs)
@@ -91,14 +89,7 @@ internal class DispatcherImpl : IDispatcherImplWithExplicitBackgroundProcessing
 
     private void CheckSignaled()
     {
-        bool signaled;
-        lock (_sync)
-        {
-            signaled = _signaled;
-            _signaled = false;
-        }
-
-        if (signaled)
+        if (Interlocked.Exchange(ref _signaled, 0) != 0)
         {
             Signaled?.Invoke();
         }

src/iOS/Avalonia.iOS/InputHandler.cs

@@ -308,7 +308,7 @@ internal sealed class InputHandler
         
         _tl.Input?.Invoke(new RawMouseWheelEventArgs(
             _mouseDevice, 
-            (ulong)(DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()), 
+            (ulong)Environment.TickCount64, 
             Root,
             _cachedScrollLocation ?? new Point(0, 0),
             new Vector(deltaX, deltaY),
@@ -372,7 +372,7 @@ internal sealed class InputHandler
         // until the inertia stops.
         _tl.Input?.Invoke(new RawMouseWheelEventArgs(
             _mouseDevice, 
-            (ulong)(DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()), 
+            (ulong)Environment.TickCount64, 
             Root,
             _cachedScrollLocation.Value,
             new Vector(_momentumVelocityX, _momentumVelocityY),

src/iOS/Avalonia.iOS/TextInputResponder.cs

@@ -84,6 +84,7 @@ partial class AvaloniaView
         private int _inSurroundingTextUpdateEvent;
         private readonly UITextPosition _beginningOfDocument = new AvaloniaTextPosition(0);
         private readonly UITextInputStringTokenizer _tokenizer;
+        private readonly NSString _textInputContextIdentifier = new NSString(Guid.NewGuid().ToString());
         private bool _isInUpdate;
 
         public TextInputMethodClient? Client => _client;
@@ -95,7 +96,7 @@ partial class AvaloniaView
         public override UIEditingInteractionConfiguration EditingInteractionConfiguration =>
             UIEditingInteractionConfiguration.Default;
 
-        public override NSString TextInputContextIdentifier => new NSString(Guid.NewGuid().ToString());
+        public override NSString TextInputContextIdentifier => _textInputContextIdentifier;
 
         public override UITextInputMode TextInputMode
         {