[Glitch] Emoji Rendering Efficiency

Port 6bca52453a to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/utils/performance.ts

@@ -0,0 +1,19 @@
+//
+// Tools for performance debugging, only enabled in development mode.
+// Open up Chrome Dev Tools, then Timeline, then User Timing to see output.
+
+import * as marky from 'marky';
+
+import { isDevelopment } from './environment';
+
+export function start(name: string) {
+  if (isDevelopment()) {
+    marky.mark(name);
+  }
+}
+
+export function stop(name: string) {
+  if (isDevelopment()) {
+    marky.stop(name);
+  }
+}