add bench util

frontend/app/utils/bench.ts

@@ -0,0 +1,8 @@
+export function bench<T>(fn: () => T, label: string = 'bench'): T {
+  const d = performance.now();
+  const r = fn();
+  const dd = performance.now();
+  // eslint-disable-next-line no-console
+  console.info(label, dd - d);
+  return r;
+}