React Performance

Priority: P0 (CRITICAL)

Strategies to minimize waterfalls, bundle size, and render cost.

Elimination of Waterfalls (P0)

• Parallel Data: Use

  Promise.all([getUser(), getProducts(), ...])

  for independent fetches. Avoid sequential awaits (Request Waterfalls).
• Preload: Start fetches before render (in event handlers or route loaders).
• Suspense: Use Suspense boundaries to stream partial content and show partial content early.

Bundle Optimization (P0)

• No Barrel Files: Avoid barrel files (importing from index.ts); import directly from component files to improve tree-shaking.
• Lazy Load: Use

  React.lazy

  or

  next/dynamic

  for heavy components like Charts, Modals, or large libraries.
• Dependency Reduction: Replace moment with dayjs or lodash with native/radash to drop bytes. Use

  source-map-explorer

  or

  bundle-visualizer

  to find bloat.

Rendering & Re-renders (P1)

• Isolation: Move state as close to its usage as possible. Isolate heavy UI updates.
• List Performance: Use

  react-window

  or

  react-virtual

  for virtualization of lists with 500+ items. Wrap list items in

  React.memo

  .
• Context Splitting: Split Context into

  State

  and

  Dispatch

  objects. This prevents all consumers from re-rendering when only a setter is needed.
• Stability: Use

  useMemo

  for derived list data and passing stable object/array references to children.
• Content Visibility:

  content-visibility: auto

  for off-screen CSS content.
• Static Hoisting: Extract static objects/JSX outside component scope.
• Transitions:

  startTransition

  for non-urgent UI updates.

Parallelization (P1)

• Web Workers: Move heavy computation (Encryption, Image processing, Large Data Sorting) off the main thread using

  Comlink

  or

  Worker

  .

Server Performance (RSC) (P1)

• Caching:

  React.cache

  for per-request deduplication.
• Serialization: Minimize props passing to Client Components (only IDs/primitives).

Anti-Patterns

• No

  export *

  : Breaks tree-shaking.
• No Sequential Await: Causes waterfalls.
• No Inline Objects:

  style={{}}

  breaks strict equality checks (if memoized).
• No Heavy Libs: Avoid moment/lodash (use dayjs/radash).

References

See references/REFERENCE.md for Profiler usage, bundle analysis, Web Workers, and debounce patterns.