Performance audit and fixes for a sluggish React analytics dashboard

Interaction latency is killing us in sales demos. Our analytics dashboard renders large tables and a dozen charts, and on customer datasets above ~50k rows the tab becomes barely usable - typing in filters lags, chart re-renders block the main thread, memory climbs until the tab dies. First week: profile the app properly (React DevTools, Chrome performance traces) and deliver a written diagnosis ranked by impact. Second week: implement the top fixes together with our frontend lead - we expect the usual suspects (unmemoized context, render waterfalls, no virtualization) but want evidence, not guesses. The app is React 18 with Next.js and TypeScript. Short, intense engagement. You will pair with our lead two or three times, otherwise work independently. Please include one sentence in your proposal about the worst React performance bug you ever found - it is how we filter template applications.