From 0c5a6d565cc7b7ea70bd3249d349dd825093bcb5 Mon Sep 17 00:00:00 2001
From: kilyabin <65072190+kilyabin@users.noreply.github.com>
Date: Thu, 18 Jun 2026 02:33:23 +0400
Subject: [PATCH] perf: fix WaitUntil being bypassed by request_redraw in
 AboutToWait

Calling request_redraw() inside AboutToWait immediately woke the event
loop on every iteration, making WaitUntil a no-op and producing a
busy-loop (98% CPU). Move request_redraw to NewEvents(ResumeTimeReached)
so the thread actually sleeps between frames.
---
 src/app.rs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/app.rs b/src/app.rs
index 3bd56a5..075cff1 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -4,7 +4,7 @@ use std::time::{Duration, Instant};
 
 use anyhow::Result;
 use winit::{
-    event::{ElementState, Event, KeyEvent, WindowEvent},
+    event::{ElementState, Event, KeyEvent, StartCause, WindowEvent},
     event_loop::{ControlFlow, EventLoop},
     keyboard::{KeyCode, PhysicalKey},
     window::{Fullscreen, WindowBuilder},
@@ -139,9 +139,14 @@ pub fn run(config: Config, monitor_idx: usize) -> Result<()> {
                 }
             }
 
+            // Timer expired or first run — schedule a redraw
+            Event::NewEvents(StartCause::ResumeTimeReached { .. } | StartCause::Init) => {
+                window.request_redraw();
+            }
+
+            // All events processed — sleep until next frame
             Event::AboutToWait => {
                 elwt.set_control_flow(ControlFlow::WaitUntil(Instant::now() + frame_time));
-                window.request_redraw();
             }
 
             _ => {}