First time I have heard that Jamba-Quest is a bit of a resource hog. It stores minimal data and only fires off events, FWIW.

I've not come accross FPS drops like this, but if you want help fixing, disable all Jamba modules and them in back one at a time, until the FPS drops come back.

Start with just enabling the parent Jamba and see what that does (no modules). Let me know how you get on...