4.16.3 Huge performance issue

While opening any project in 4.16.3 I get a huge performance drop from Prepass, and [unaccounted].
Occasionally, the performance hit will be HZB instead. The frame times are upwards of 40ms.
It only occurs on this particular computer, and only in 4.16.3
Other unreal versions work great on this computer, and the same projects work fine on other computers in 4.16.3
I tried reinstalling 4.16.3 but no luck.

I found out the problem was my Gsync monitor. Turning Gsync off in the Nvidia Control Panel fixed the problem.