Most teams know their app is slow. They just don't know which part, so they guess - and end up with marginal improvements and no idea what actually helped.

I profile first, then change things. I've cut page load times by 30% on a production React app and reduced API response times by 25% on a mobile app. Both came from measuring what was slow, not assuming.

Full audit using Lighthouse, Chrome DevTools Performance Panel, React DevTools Profiler, and Web Vitals

Finding unnecessary re-renders and missing memoization

Bundle size analysis with code splitting applied where it helps

Lazy loading for components, routes, and images

API optimization - less over-fetching, caching added where it's missing

GraphQL query optimization if you're using it

Image optimization and modern format delivery (WebP, AVIF)

Core Web Vitals improvements targeting LCP, CLS, and FID

Written report of every problem found and every fix applied

Before and after numbers for every meaningful change

If your app is already fast, I'll tell you that rather than inventing work. Some codebases are in good shape - that's a fine outcome.