High latency in Node.js servers can stem from inefficient database queries, blocked event loops, or unoptimized code. Identifying bottlenecks with profiling tools is essential.

High latency in a Node.js server can often be traced to a combination of blocked event loops, inefficient database queries, and unoptimized request-handling code. Blocked event loops occur when CPU-bound tasks or heavy computations are executed in a way that holds up the non-blocking nature of Node.js, so to counter this, you can delegate such tasks to worker threads or offload them to background processes to keep the main thread free for fast response times. Another common source is the database: slow queries, lack of indexing, or an over-reliance on sequential queries that could otherwise be batched or optimized are frequent culprits. Proper profiling is vital, so using tools like Chrome DevTools or the node --inspect command can allow you to identify exactly where requests are slowing down. Additionally, caching can drastically reduce latency for repetitive tasks, especially for data that doesn’t change often, and implementing an in-memory cache or leveraging tools like Redis can reduce the number of times the server needs to pull information from disk or a remote database. Load balancing and using a content delivery network (CDN) for static assets also play a role in reducing load on a single server, improving request handling and allowing for smoother traffic distribution. Furthermore, performing asynchronous I/O operations wherever possible helps prevent blocking the event loop; using async functions for network requests and file operations can cut down response times significantly, as synchronous operations often delay request handling. In summary, a combination of load balancing, effective caching, optimized database queries, and efficient event loop management will greatly enhance your Node.js server’s latency profile, making it more resilient to high traffic and large numbers of simultaneous requests.