EGLL Performance

[Lude2Envy 17]

I'm sorry for writing this post because I am not one to complain, especially in forums, but I really just do not understand why Heathrow Xtended has such terrible performance in FSX. The frames are awful and the OOMs are even worse. I own almost every scenery from FSDT, FlyTampa, Flightbeam, and Taxi2Gate, but none of them hit my system the way EGLL Xtended does. I run FSX on max settings (except water) with REX 4 Textures, PMDG/FSL/MJS/LSH aircraft, FTX Global/Vector, UT2 traffic, and all of my airports with no problems whatsoever. There is clearly something wrong with EGLL. I don't want to hear that I need to turn my settings down because I shouldn't have to. EGLL is not that complex of an airport - especially compared to FSDT DFW. When I can takeoff from T2G VHHH with the PMDG 777 and fly over FlyTampa Kai-Tak with no problems, why are my frames crushed just taxiing around EGLL and then FSX is running OOM shortly after takeoff? I'm sorry, but it doesn't make any sense.