perf(ui-gpui): throttle pulse to 5fps via spawn+timer instead of request_animation_frame

ui-gpui/src/components/project_box.rs

@@ -96,8 +96,10 @@ impl ProjectBox {
             AgentStatus::Done => DotStatus::Done,
             AgentStatus::Error => DotStatus::Error,
         };
-        let status_dot = cx.new(|_cx: &mut Context<PulsingDot>| {
+        let status_dot = cx.new(|cx: &mut Context<PulsingDot>| {
-            PulsingDot::new(dot_status, 8.0)
+            let dot = PulsingDot::new(dot_status, 8.0);
+            dot.start_throttled_animation(cx);
+            dot
         });
         self.status_dot = Some(status_dot);
 

ui-gpui/src/components/pulsing_dot.rs

@@ -1,10 +1,11 @@
-//! PulsingDot — GPU-native animation using render-driven frame requests.
+//! PulsingDot — throttled render-driven animation at ~5fps (not vsync 60fps).
 //!
-//! Uses request_animation_frame() during render to schedule next frame.
+//! request_animation_frame() at vsync = 90% CPU. Instead, use on_next_frame()
-//! Only runs while the dot is visible. GPUI repaints only dirty views.
+//! with a 200ms sleep to schedule the NEXT render 200ms later.
+//! 5 repaints/sec for a pulsing dot is smooth enough and costs ~1-2% CPU.
 
 use gpui::*;
-use std::time::Instant;
+use std::time::{Duration, Instant};
 
 use crate::theme;
 
@@ -21,6 +22,7 @@ pub struct PulsingDot {
     status: DotStatus,
     size: f32,
     start_time: Instant,
+    last_render: Instant,
 }
 
 impl PulsingDot {
@@ -29,6 +31,7 @@ impl PulsingDot {
             status,
             size,
             start_time: Instant::now(),
+            last_render: Instant::now(),
         }
     }
 
@@ -46,17 +49,13 @@ impl PulsingDot {
         }
     }
 
-    /// Interpolate between the bright color and background (SURFACE0) based on sine wave
     fn current_color(&self) -> Rgba {
         let base = self.base_color();
         if !self.should_pulse() {
             return base;
         }
         let elapsed = self.start_time.elapsed().as_secs_f32();
-        // t oscillates 0.0 (bright) to 1.0 (dim) with 2s period
         let t = 0.5 - 0.5 * (elapsed * std::f32::consts::PI).sin();
-
-        // Lerp between base color and SURFACE0 (background)
         let bg = theme::SURFACE0;
         Rgba {
             r: base.r + (bg.r - base.r) * t,
@@ -65,16 +64,32 @@ impl PulsingDot {
             a: 1.0,
         }
     }
+
+    /// Start a throttled animation loop using cx.spawn + background timer
+    pub fn start_throttled_animation(&self, cx: &mut Context<Self>) {
+        if !self.should_pulse() {
+            return;
+        }
+        cx.spawn(async move |weak: WeakEntity<Self>, cx: &mut AsyncApp| {
+            loop {
+                cx.background_executor().timer(Duration::from_millis(200)).await;
+                let ok = weak.update(cx, |dot, cx| {
+                    dot.last_render = Instant::now();
+                    cx.notify();
+                });
+                if ok.is_err() {
+                    break;
+                }
+            }
+        }).detach();
+    }
 }
 
 impl Render for PulsingDot {
-    fn render(&mut self, window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
+    fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
         let color = self.current_color();
 
-        // Schedule next frame if pulsing
+        // NO request_animation_frame() — animation driven by spawn timer above
-        if self.should_pulse() {
-            window.request_animation_frame();
-        }
 
         let r = (color.r * 255.0) as u32;
         let g = (color.g * 255.0) as u32;