I too am experiencing the same scenario, Got a new rig 2 weeks ago, and ever since I'm trying to tweak it to run at a reasonable fps considering that I do run UT2 and ORBX Global.
My goal is to get autogen geenration (currently slow)and texture popups fix with a minimum 12-15FPS in heavy metropolitan areas. I'm not asking for smoothness but rather playable so I can land the damn plan on the ground without jerking it around.
Current setup:
I7 4770K 3.5 (OC 4.4)
Asus Radeon R9 290X 4gb
2x8gb RAM 1866 R9 DDR3
Win7 64bit
Corsair h80i Liquid cooler
PS 750watts
Already tried playing with bufferpools, I am runing an ATI card so I'm using external FPS limiter (been proven to give me greater FPS) while in game set to unlimited. I think rejectthershold works best vs usepools (at least for me). CCC was adjusted to recomended setting for antialiasing and such... HImemfix was applied.
I remember I applied the http://www.venetubo.com/fsx tweak to my cfg file with my old computer and we're talking about a 5 year old rig and I was getting a decent experience of 10-12 FPS in JFK and area, which is playable. Unfortunately the site is down and I'm not sure if there's anything similar to it anymore where I could apply to get a similar experiance if not better.
Moshwing