Merge pull request #3083 from Domanffe/perf/hud-paint-reuses-sprite-key

🤖 Agent: read the diff at 4bf633e8a ("HUD paint: build the sprite key in one reused buffer") against the 26.3 source it cites; verify green, merges cleanly with main. Proof: cg25 union a051cc285 (local branch cg25/union in t3-ef805fdb: main 6d3489d30 + 38 contributor heads merged cleanly, no fixups): clippy -p horizon-client --all-targets -D warnings clean, horizon-client lib 1105 + bin 133 + integration tests pass, parity --changed 355/355 harnesses PASS on the Mac mini (Cargo.lock changed by #3210, so every harness ran; tab_list passed on its one retry).

crates/horizon-client/src/hud_layout.rs

@@ -801,6 +801,8 @@ impl HealthHud {
 /// nausea blits (their blending needs the screen-effect pipeline).
 pub fn paint(batch: &mut crate::hud::HudBatch, atlas: &crate::hud::HudAtlas, draws: &[GuiDraw]) {
     let mut stack = vec![IDENTITY];
+    // One buffer for the sprite keys, instead of a string per drawn sprite.
+    let mut name = String::new();
     for d in draws {
         let start = batch.vertices.len();
         let pose = *stack.last().unwrap_or(&IDENTITY);
@@ -817,12 +819,14 @@ pub fn paint(batch: &mut crate::hud::HudBatch, atlas: &crate::hud::HudAtlas, dra
             } => {
                 // Effect sprites belong to the mob_effect atlas directory;
                 // the other blitSprite ids refer to GUI sprites.
-                let name = if sprite.starts_with("mob_effect/") {
-                    sprite.to_string()
+                name.clear();
+                if sprite.starts_with("mob_effect/") {
+                    name.push_str(sprite);
                 } else {
-                    format!("gui/sprites/{sprite}")
-                };
-                let Some(mut r) = atlas.sprites.get(&name).copied() else {
+                    name.push_str("gui/sprites/");
+                    name.push_str(sprite);
+                }
+                let Some(mut r) = atlas.sprites.get(name.as_str()).copied() else {
                     continue;
                 };
                 if let Some([sw, sh, u, v]) = *region {