Problem: As stated, even though you have an SSD and nothing else is running.
Solution: Counterintuitively, you have to disable hardware graphics acceleration in Powerpoint. It is likely that will clear it right up.
Why you have to turn hardware-based acceleration OFF to get BETTER performance is beyond me, and one more example of how ridiculous things have gotten.
Yes, I know 2010 is very old now. But it's possible this might affect other versions / systems, or even extend beyond Powerpoint itself.