When I got my G2 I also had FPS issues that I just could not understand. After trying a number of things that made no difference I noticed that the CPU lua usage was really high. Turned out that export.lua was the culprit, after deleting it (it gets recreated) my frame rate improved a lot. Now DSC is like a new game, coming from the Rift S the Reverb G2 is nothing short of a revolution.