events: lazy load perf_hooks for EventTarget

PR-URL: #33717
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Zeyu Yang <[email protected]>
Reviewed-By: Denys Otrishko <[email protected]>
Reviewed-By: Juan José Arboleda <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>

Author: jasnell

lib/internal/event_target.js

@@ -19,7 +19,6 @@ const {
   }
 } = require('internal/errors');
 
-const perf_hooks = require('perf_hooks');
 const { customInspectSymbol } = require('internal/util');
 const { inspect } = require('util');
 
@@ -30,11 +29,19 @@ const kTarget = Symbol('kTarget');
 const kNewListener = Symbol('kNewListener');
 const kRemoveListener = Symbol('kRemoveListener');
 
+// Lazy load perf_hooks to avoid the additional overhead on startup
+let perf_hooks;
+function lazyNow() {
+  if (perf_hooks === undefined)
+    perf_hooks = require('perf_hooks');
+  return perf_hooks.performance.now();
+}
+
 class Event {
   #type = undefined;
   #defaultPrevented = false;
   #cancelable = false;
-  #timestamp = perf_hooks.performance.now();
+  #timestamp = lazyNow();
 
   // None of these are currently used in the Node.js implementation
   // of EventTarget because there is no concept of bubbling or