Just recently, I also have high CPU usage (50%) with PTP 2.17 and 2.21. I think it started after I flashed to 1.05 about 10 days ago (I am now on 1.06 a few days ago and same issue), and it stays at 50% even after burning is complete and DVDDcryter is closed.
I first got concerned when I would shut down system, I get: "End Program-Plextools Professional 2.21- the program is not responding (plus the rest of the verbiage about loosing unsaved data), and upon further investigation (today) is when I noticed the CPU usage stuck at 50%. At this point, you cannot 'Retore or Exit' PTP from the systray. You have to reboot the system. Only then will PTP be at 00% CPU usage.
About the same time before I flashed to v1.06, I also loaded DVDFab Gold for the first time on this system (their latest v).
I re-installed PTP 2.21, but no joy.
Thanks in advance for your help, Best Regards.