bun:optimize

Bun Optimization

Analyze and optimize Bun application performance.

Optimization Areas

Bundle Size Optimization

Analyze current bundle:

const result = await Bun.build({
  entrypoints: ["./src/index.ts"],
  outdir: "./dist",
  minify: true,
  splitting: true,
  sourcemap: "external",
});

for (const output of result.outputs) {
  console.log(`${output.path}: ${output.size} bytes`);
}

Techniques:

1. Enable minification - Reduces size by 40-60%
2. Code splitting - Lazy load non-critical code
3. Tree shaking - Remove unused exports
4. External packages - Don't bundle large deps
5. Drop console/debugger - Remove dev code

await Bun.build({
  entrypoints: ["./src/index.ts"],
  outdir: "./dist",
  minify: true,
  splitting: true,
  drop: ["console", "debugger"],
  external: ["react", "react-dom"],
});

Runtime Performance

1. Use Bun APIs - Prefer Bun.file() over fs
2. Stream large files - Don't load into memory
3. Prepared statements - Reuse SQLite statements
4. Connection pooling - For databases
5. Response caching - Cache expensive operations

// Good: Stream large files
const file = Bun.file("large.json");
const stream = file.stream();

// Good: Prepared statements
const stmt = db.prepare("SELECT * FROM users WHERE id = ?");
for (const id of ids) {
  stmt.get(id);
}

// Good: Cache responses
const cache = new Map();
async function getData(key) {
  if (cache.has(key)) return cache.get(key);
  const data = await fetchData(key);
  cache.set(key, data);
  return data;
}

Memory Optimization

1. Use --smol flag - Reduces memory footprint
2. Stream processing - Avoid loading all data
3. WeakMap/WeakSet - For cached objects
4. ArrayBuffer reuse - Pool buffers
5. Avoid closures - In hot paths

# Run with reduced memory
bun --smol run src/index.ts

// Good: Stream processing
for await (const line of file.stream()) {
  processLine(line);
}

// Good: Buffer pooling
const bufferPool = [];
function getBuffer(size) {
  return bufferPool.pop() || new ArrayBuffer(size);
}
function releaseBuffer(buf) {
  bufferPool.push(buf);
}