What are the complete computer specs, including hard drives (how many, what kind, what is on each, what capacity, and how full)?
If NVIDIA graphics, make sure to use the latest Studio Driver from NVIDIA (NOT the Game Driver).
Well I use Apowersoft
Please use the free MediaInfo and post a screenshot the properties of your media in tree view:
Many users are having issues with VFR. If the file is variable frame rate, use Hand brake to convert to constant frame rate:
Here is a tutorial: