I'm quite enjoying playing with the Tracy profiler. Turns out when you run the program with sudo, it records a ton of extra useful info, like CPU core scheduling, monitor VSync events, kernel context switches, what your process is blocked on.
I also annotated my compositor with Tracy Frame events for monitor VBlank cycles. I can then set a target FPS in Tracy and instantly see which frames were too slow! Both in the bar at the top, and in the main area highlighted in red.