I have this to.I found out what is causing this, though i have no clue how to "fix" the issue. If you click on your name where it lists all the civs score if minimizes the scores except yours, and your slowness with completely disappear. And if you maximize it again it will slowdown to like 2 FPS again.
Why is there an Inquisitors Game Option in the custom game menu? Is it not already in the RevDCM options page?
Is this meant to be a teaser?Lots of customizable features in the Global Defines Alt, check them out!