CPU Profiling and Identifying Event Loop Blockage

Use the --inspect flag and Chrome DevTools Profiler to identify 'Long Tasks' and flame graphs that show where the main thread is spending too much time.

If an API takes 500ms to respond but DB queries take only 10ms, the Event Loop is likely blocked by heavy JS execution (e.g., parsing a 50MB JSON). Profiling generates a 'Flame Graph'. Wide bars indicate functions that stayed on the stack for a long time. Senior engineers look for 'Hot Functions' that can be optimized or moved to Worker Threads.