Timers in Node.js can behave inconsistently due to event loop delays, especially under heavy load. Profiling the event loop with `clinic` or `perf_hooks` can help pinpoint issues.

Inconsistent behavior with timers like setTimeout() or setInterval() in Node.js often points to event loop delays, which can happen when your app is under heavy load or processing blocking code. The event loop is responsible for executing scheduled timers, but if it’s blocked by CPU-heavy tasks or synchronous I/O, timers can get delayed. To debug this, you can use tools like clinic or the built-in perf_hooks module to profile the event loop and find out where the delays are coming from. Offloading heavy computations to worker threads or child processes can reduce the load on the event loop, ensuring that timers fire on time. By optimizing your event loop, you can avoid inconsistent timer behavior and maintain performance.