Member-only story
Why Frontend Engineers Need to Understand Performance
Your app works. Your users still leave. Here’s what’s actually happening.
It Passed Code Review
Your PR is clean. The logic is correct. Tests are green. A senior engineer approved it.
You deploy on Thursday afternoon.
By Friday morning, the product manager sends a Slack message: “Users are complaining the app feels slow.”
You open Chrome DevTools. Everything looks fine on your MacBook Pro, on your home fiber connection, in your Chrome profile with 12 extensions disabled.
But your users aren’t you.
They’re on a mid-range Android phone from 2021. On a 4G connection that keeps dropping to 3G. In Jakarta, Lagos, Baku — cities where network latency alone adds 200–400ms to every request.
And your app is making them wait.
Why This Gap Exists
Most frontend engineers develop under ideal conditions and deploy for real-world ones. The gap between those two environments is where performance problems live.
Here’s what your development setup hides from you:
CPU throttling. Your laptop has a fast processor. Chrome DevTools lets you simulate 4x or 6x CPU slowdown —…
