From Minecraft Wiki
Starts or stops a debugging session.
- Starts a new debug profiling session.
- Stops the active debug profiling session.
- Fails if trying to start a debug session when one is already active, or if trying to stop a debug session when none is running.
- On success, starts or stops the debug session. While active, includes notifications about potential performance bottlenecks in the console. When stopped, creates a profiler results file in the folder "debug".