Performance Optimization

Rationale

Optimizing performance improves user experience, reduces resource usage, and supports scalability. Regular profiling and optimization help prevent slowdowns and outages.

Caching

Use caching to store expensive computations, API responses, or rendered templates. Use browser or server-side caches as appropriate.

Example (Browser):

// Good: Use localStorage for caching API responses
const cached = localStorage.getItem('userData');
if (cached) {
  renderUser(JSON.parse(cached));
} else {
  fetch('/api/user').then(res => res.json()).then(data => {
    localStorage.setItem('userData', JSON.stringify(data));
    renderUser(data);
  });
}

Example (Node.js):

// Good: Use in-memory cache
const cache = {};
function getExpensiveResult(key) {
  if (cache[key]) return cache[key];
  const result = computeExpensiveResult(key);
  cache[key] = result;
  return result;
}

Async Operations

Use asynchronous programming (Promises, async/await) to improve performance and responsiveness.

Example:

// Good: Use async/await for non-blocking code
async function loadData() {
  const data = await fetch('/api/data').then(res => res.json());
  // ...
}

// Bad: Synchronous blocking
function loadData() {
  const xhr = new XMLHttpRequest();
  xhr.open('GET', '/api/data', false); // blocks UI
  xhr.send();
  // ...
}

• Use Promises, async/await, and event-driven patterns for responsiveness.

Profiling

Profile code using browser dev tools or Node.js profilers to identify bottlenecks and optimize critical paths.

Example:

• Use Chrome DevTools Performance tab to record and analyze slow code.
• Use Node.js --inspect and clinic.js for server-side profiling.

Best Practices

• Profile and monitor application performance regularly.
• Cache expensive operations and static content.
• Optimize code and data structures for speed and efficiency.
• Lazy load images, components, and modules where possible.
• Minify and compress assets for faster delivery.
• Monitor performance in production and address bottlenecks.
• Document performance strategies for new team members.