Profile it. If the profiler points to some awful thousand-line method and the cause isn't obvious, add logging statements to record elapsed time at several poi

Profile it. If the profiler points to some awful thousand-line method and the cause isn't obvious, add logging statements to record elapsed time at several points within the method; use that to narrow down the cause. Common culprits: nested loops (sometimes hidden by looping over function calls that contain loops of their own); database abuse; calls out to third-party services.