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]>
nodejs · Jun 18, 2020 · f1b0291 · f1b0291
1 parent d427d7f
commit f1b0291
Showing 1 changed file with 9 additions and 2 deletions.
diff --git a/lib/internal/event_target.js b/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