YAFSPT (Yet Another FS Performance Thread)

I am one of those poor unfortunates who can't (couldn't) get FS to run at a decent lick. However, I suspect I have at last found the problem. I have always run with UK2000 airports, Genesis UK mesh and UK landclass. However, recently I bought MyWorld world landclass. No difference. I also bought the F1 ATR, it then ran a little bit slower in that a/c as one might expect. We a talking 6-8 FPS landing somewhere like Southampton UK with 100% default AI + UK2000 AI and about 13 FPS most other times. Heathrow was out of the question.I have always run with these scenery addons as otherwise I wouldn't bother. Anyway, I also most recently bought FS Global. This replaces my Genesis mesh and now I seem to have a constant 14.8 FPS with the sim locked at 15 FPS...everywhere!?!!? (and in the F1 ATR).The UK Genesis mesh is not of any higher resolution than FS Global so what gives?Please please don't ditch Genesis or buy FS Global on my account, I just want to compare notes.