The “wake up” time of the GPU might be expected and I don’t know, if you can avoid it, since the GPU would reduce it’s Perf to use less power (as seen via nvidia-smi) if no workload is currently executed.
What I don’t know, is why time.sleep interferes with the profiling, but I’m also not an expert in Python mutliprocessing and don’t know if the main process is just suspended for the specified amount of time or if “more” is happening under the hood.