From 23d78a90d4cee0d260f33fb989168b9c7ae15184 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Fri, 23 Jan 2026 18:47:00 +0000
Subject: [PATCH] perf(drw): replace XSync with XFlush in drw_map for
 non-blocking drawing

Using XSync forces a round-trip to the X server, blocking the client until the server processes the request. For frequent drawing operations like drw_map, this introduces unnecessary latency. XFlush ensures the request is sent without waiting for a response, significantly improving responsiveness during updates.
---
 .jules/bolt.md | 3 +++
 drw.c          | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 00000000..5d46ba9f
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2026-01-23 - XSync vs XFlush in drw_map
+**Learning:** In X11 window managers, using XSync in frequent drawing paths (like drw_map) causes blocking round-trips to the X server, significantly degrading performance.
+**Action:** Use XFlush for drawing operations where synchronous confirmation is not required.
diff --git a/drw.c b/drw.c
index 7e99a386..66e008bf 100644
--- a/drw.c
+++ b/drw.c
@@ -494,7 +494,9 @@ void drw_map(Drw *drw, Window win, int x, int y, unsigned int w,
     }
 
     XCopyArea(drw->dpy, drw->drawable, win, drw->gc, x, y, w, h, x, y);
-    XSync(drw->dpy, False);
+    /* XFlush is used here instead of XSync to avoid blocking round-trips
+     * during frequent drawing operations. */
+    XFlush(drw->dpy);
 }
 
 unsigned int drw_fontset_getwidth(Drw *drw, const char *text) {