fix: temporary fix for fps drop issue when starting stream with graph disabled

VoidLink/ImGuiRenderer.h

@@ -20,6 +20,7 @@ typedef void (^MetricsHandler)(int plotId, CFTimeInterval value);
 @property (nonatomic) FloatBuffer * _Nonnull frametimes;
 @property (nonatomic) BOOL enableGraphs;
 @property (nonatomic) float graphOpacity;
+@property (nonatomic) int streamFps;
 @property (nonatomic) BOOL imguiRunning;
 @property (nonatomic) MetricsHandler _Nonnull metricsHandler;
 

VoidLink/ImGuiRenderer.mm

@@ -30,6 +30,7 @@
     _enableGraphs = enableGraphs;
     _graphOpacity = (float)(graphOpacity / 100.0);
     _bounds = bounds;
+    _streamFps = streamFps;
     _device = MTLCreateSystemDefaultDevice();
     _commandQueue = [_device newCommandQueue];
 
@@ -83,34 +84,46 @@
 
     self.mtkView.device = self.device;
     self.mtkView.delegate = self;
-    self.mtkView.preferredFramesPerSecond = 60; // ImGui overlay will always render at this rate
+    self.mtkView.preferredFramesPerSecond = _streamFps; // Match the stream frame rate for proper display sync
     self.mtkView.opaque = NO;
     self.mtkView.enableSetNeedsDisplay = NO;
 
     if (_enableGraphs) {
         [self ImGui_Init];
         self.mtkView.paused = NO;
+        self.mtkView.hidden = NO;
     }
     else {
-        self.mtkView.paused = YES;
+        // Keep Metal view running for display sync but don't initialize ImGui
+        self.mtkView.paused = NO;
+        self.mtkView.hidden = YES; // Hide but keep running for display sync
     }
 }
 
 // start & stop are used to show/hide graphs when swiping stats in or out
 -(void)start {
-    [self ImGui_Init];
     if (_enableGraphs) {
-        self.mtkView.paused = NO;
+        [self ImGui_Init];
+        self.mtkView.hidden = NO;
+    } else {
+        // Keep running for display sync but stay hidden
+        self.mtkView.hidden = YES;
     }
+    self.mtkView.paused = NO;
 }
 
 -(void)show {
+    if (_enableGraphs) {
         [self.mtkView setHidden:NO];
     }
+}
 
 -(void)hide {
+    if (_enableGraphs) {
         [self.mtkView setHidden:YES];
     }
+    // When graphs are disabled, ImGui stays hidden but keeps running for display sync
+}
 
 -(void)stop {
     self.mtkView.paused = YES;
@@ -120,14 +133,6 @@
 // Only called when mtkView.paused is false
 - (void)drawInMTKView:(MTKView *)view
 {
-#if !defined(IMGUI_DISABLE)
-    ImGuiIO &io = ImGui::GetIO();
-    io.DisplaySize.x = view.bounds.size.width;
-    io.DisplaySize.y = view.bounds.size.height;
-
-    CGFloat framebufferScale = view.window.screen.scale ?: UIScreen.mainScreen.scale;
-    io.DisplayFramebufferScale = ImVec2(framebufferScale, framebufferScale);
-
     id<MTLCommandBuffer> commandBuffer = [self.commandQueue commandBuffer];
 
     MTLRenderPassDescriptor* renderPassDescriptor = view.currentRenderPassDescriptor;
@@ -136,6 +141,15 @@
         return;
     }
 
+    if (_enableGraphs) {
+#if !defined(IMGUI_DISABLE)
+        ImGuiIO &io = ImGui::GetIO();
+        io.DisplaySize.x = view.bounds.size.width;
+        io.DisplaySize.y = view.bounds.size.height;
+
+        CGFloat framebufferScale = view.window.screen.scale ?: UIScreen.mainScreen.scale;
+        io.DisplayFramebufferScale = ImVec2(framebufferScale, framebufferScale);
+
         // Start the Dear ImGui frame
         ImGui_ImplMetal_NewFrame(renderPassDescriptor);
         ImGui::NewFrame();
@@ -161,15 +175,25 @@
         ImGui_ImplMetal_RenderDrawData(draw_data, commandBuffer, renderEncoder);
         [renderEncoder popDebugGroup];
         [renderEncoder endEncoding];
+#endif
+    } else {
+        // When graphs are disabled, just render a transparent frame for display sync
+        renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(0.0, 0.0, 0.0, 0.0);
         
-    // Present
+        id <MTLRenderCommandEncoder> renderEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];
+        [renderEncoder pushDebugGroup:@"Display sync frame"];
+        // Don't render anything, just clear
+        [renderEncoder popDebugGroup];
+        [renderEncoder endEncoding];
+    }
+
+    // Present (always with timing for display sync)
 #if TARGET_OS_SIMULATOR
     [commandBuffer presentDrawable:view.currentDrawable];
 #else
     [commandBuffer presentDrawable:view.currentDrawable afterMinimumDuration:1.0 / view.preferredFramesPerSecond];
 #endif
     [commandBuffer commit];
-#endif
 }
 
 - (void)mtkView:(MTKView *)view drawableSizeWillChange:(CGSize)size