christoole wrote on Jan 10^th, 2008 at 8:10pm:

Just as a follow-up to my earlier post, SP2 *did* make an appreciable difference to framerates, so would recommend this. Chris

Yep, I've just found exactly the same thing, with Base Pack 1.1.  On FSX SP1 I was getting 3-5 FPS :'(, even with sliders well down. Now on FSX SP2 I'm getting 15-20 FPS :) with sliders fairly well up.