I've installed v12 trial and read the help file.
Enabling Hardware/Software Decoding
At the top of the Videos tab of the TrueTheater Technology window, you can enable hardware or software decoding for smoother video playback.
• Enable hardware decoding acceleration: if your computer supports NVIDIA CUDA/AMD Accelerated Parallel Processing technology, select Enable NVIDIA CUDA/AMD Accelerated Parallel Processing to use GPU acceleration to decode the video for smoother movie playback. When selected, the TrueTheater Effects are disabled.
• Enable software decoding without TrueTheater Effects: select this option if you want to use CyberLink's built in codec to decode the video for smoother movie playback. When selected, the TrueTheater Effects are disabled.
• Enable software decoding with TrueTheater Effects: select this option if you want to use CyberLink's built in codec to decode the video for smoother movie playback, and enable TrueTheater Effects. Once enabled, modify the effects as required below.
So guessing v10 is similar (search cuda in the ? help) enabling hardware decoding acceleration is optimisation for Cuda if its available.
Try some of those other settings too if you haven’t already and if your movies still don’t play right perhaps there’s a patch you can apply.