The Day Our Web App Took 8 Seconds to Load (and How We Cut It in Half)

There is a quiet moment of panic every developer knows. You hit deploy, open the live site on your phone, and wait.

One second. Two seconds. Four seconds. Still a blank white screen.

A while back, I was working on a Next JS application that looked fast on high speed office Wi Fi. But when tested on a spotty mobile connection, it felt painfully slow. The initial page load was clocking in at nearly 8 seconds, and our main JavaScript bundle was a bloated 1.8 megabytes.

Here is how we diagnosed the bloat, cut our load times by 47 percent, and the simple performance rules every developer should know.

The Investigation: Where Was the Weight Coming From?