Your system seems capable. What version of Videopad is being used (look at the bottom-left of the window) and what is the PC's GPU (graphics) adapter?
Try this... Go to OPTIONS | ADVANCED (or EDITING in older versions) and in the bottom GPU area change default to None (CPU only). Any better?

Install the latest release. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee will be required in order to register the newest. Retain your old install file and registration info.
And for protection, Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the caret to the right of the Save Project button on the toolbar.