Apply this skill when building, optimising, or reviewing components, data fetching, or database queries in a Next.js App Router + TypeScript + Tailwind + shadcn + Drizzle application where performance matters. Triggers on requests like "optimise this", "this is slow", "reduce re-renders", "improve load time", "this list is laggy", "bundle is too large", "slow query", or any time you are building features that involve large lists, frequent updates, heavy computations, or significant data volumes. Use proactively for anything rendering more than ~50 items or running on every keystroke.