API Response Optimization

As a startup scaled past 50,000 users, over-fetching with SELECT * and heavy JSON serialization became major bottlenecks; strict DTOs cut response times by 30%. The team treated the Node.js event loop as a critical resource, offloading heavy synchronous work to background workers and using setImmediate() to prevent blocking. They also adopted Brotli compression over Gzip with a 1KB threshold to reduce bandwidth without wasting CPU on small payloads.