Computer specification and program version, see this topic for what is required and please quote processor and graphics card make/model in full - I would suggest you put this information in your profile signature so we do not have to keep asking for it.
Are the graphics card drivers up to date?
A screen shot of the Program settings, Display options or Device options tab.
Download and install MediaInfo and analyse one of the source video clips and post the results, see this tutorial if you are not familiar with MediaInfo on how to setup MediaInfo and analyse a video clip.