Performance overhaul of Shiftly web app
Took a sluggish single-page app from failing to passing Core Web Vitals on every key page. A case study by Pedro Alves, Junior Frontend Developer (React).
Challenge
The search results page of Shiftly, a workforce scheduling app, took over five seconds to become interactive on mid-range phones. Organic traffic had started dropping after the page experience update, and bounce rates were climbing.
Solution
I profiled the app, split the bundle by route, replaced two heavy libraries with small utilities, moved images to responsive formats and rendered the first results on the server. A performance budget in CI now fails any pull request that makes things slower.