⚡ Bolt: optimize window resizing by removing blocking XSync

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2026-01-24 - Blocking XSync in Layouts
+**Learning:** `instantwm` (and other X11 WMs) can suffer from significant latency during layout operations (like tag switching or resizing multiple windows) if `XSync` is used in the `resizeclient` hot path. `XSync` forces a round-trip to the X server for *every* window resized, which scales linearly with the number of windows (O(N)).
+**Action:** Replace `XSync` with `XFlush` in `resizeclient` (and similar hot paths like `drw_map` if safe). `XFlush` pushes the requests to the server without waiting for a reply, which is sufficient for simple geometry updates where the client doesn't need immediate feedback. This eliminates N round-trips, making layout changes effectively instantaneous from the client's perspective.

client.c

@@ -279,7 +279,8 @@ void resizeclient(Client *c, int x, int y, int w, int h) {
     XConfigureWindow(dpy, c->win,
                      CWX | CWY | CWWidth | CWHeight | CWBorderWidth, &wc);
     configure(c);
-    XSync(dpy, False);
+    /* Optimization: Use XFlush instead of XSync to avoid blocking round-trip to X server */
+    XFlush(dpy);
 }
 
 void updatetitle(Client *c) {