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Amit Gupta
Amit Gupta

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I Was Just Browsing GitHub. Three Days Later, I Was Fixing a Vue.js Memory Leak

#vue #development

It started innocently enough: I was browsing GitHub on a lazy weekend, looking through open issues on a Vue.js-based dashboard project that had recently gained traction. One thread caught my eye — a vague complaint about the app slowing down over time. No logs, no specific version numbers. Just: "The app gets really sluggish after navigating for a while."

Challenge accepted.

Tracing the Problem

I forked the repo, ran the app locally, and tried to reproduce the issue. At first, everything felt smooth. But after 5–10 minutes of heavy tab-switching and component interaction, the Chrome DevTools Performance panel showed something worrying: memory usage was climbing — and not coming down.

There was a memory leak. A slow, sneaky one.

The Vue Trap: Anonymous Functions & Untracked Listeners

After a few hours of digging, I found the culprit: a combination of anonymous event listeners inside mounted() hooks and missing cleanup logic in beforeUnmount().

mounted() {
  window.addEventListener('resize', this.handleResize);
},
// But no corresponding cleanup:
// beforeUnmount() {
//   window.removeEventListener('resize', this.handleResize);
// }
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The event listener was being added each time the component mounted (even in a dynamic list), but never removed. Multiply that by dozens of components and frequent route changes, and memory started leaking like a sieve.

The Fix

I added proper teardown logic inside the beforeUnmount() hook:

beforeUnmount() {
  window.removeEventListener('resize', this.handleResize);
}
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Then I added a name attribute to all dynamic components so Vue could cache and re-use them properly, reducing unnecessary re-renders and lifecycle hook executions.

Finally, I ran tests using Chrome's memory profiler and verified the app now released memory after navigation.

Lessons Learned

  • Always clean up side effects — especially when working with global listeners, intervals, or subscriptions.
  • Use named component caching () smartly to avoid unnecessary remounts.
  • Vue doesn’t warn you about leaks — it's up to you to profile, test, and catch them before users do.
  • Memory leaks often show up over time, so long-term profiling is just as important as load-time optimization.

Final Thoughts

I didn’t plan to contribute code that weekend — but I ended up submitting a PR, writing test cases, and talking to the maintainer about broader performance fixes. It was a reminder that Vue.js is powerful, but with great reactivity comes great responsibility.

If your team is struggling with Vue.js performance issues or scaling an existing app, we at MetaDesign Solutions—a trusted Vue.js development company—can help you fix the leaks and build for long-term success.

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