Add timer

utils/timer.ts

@@ -0,0 +1,21 @@
+import { log } from "./cli.ts";
+
+export class Timer {
+  private initialTimestamp: number;
+  private lastCheckpointTimestamp: number | null = null;
+
+  constructor() {
+    this.initialTimestamp = Date.now();
+  }
+
+  checkpoint(name: string): void {
+    const now = Date.now();
+    const duration = this.lastCheckpointTimestamp
+      ? now - this.lastCheckpointTimestamp
+      : now - this.initialTimestamp;
+
+    log.info(`${name}: ${duration}ms`);
+    this.lastCheckpointTimestamp = now;
+  }
+}
+