A friend of mine passed these on - huge improvement.
Set your antivirus software to not realtime scan the FSX folder. Flightsim is constantly loading files. With McAfee I have to turn off realtime scanning completely (set to resume on computer restart) Doing this alone bumped me by approximately 75% increase!
Add these to your FSX config file (Windows 7 here, mine is located C:\Users\Chris\AppData\Roaming\Microsoft\FSX)
in the [Graphics] section make sure this is the setting
TEXTURE_MAX_LOAD=2048
in the [Terrain] section add/modify
TERRAIN_MAX_AUTOGEN_TREES_PER_CELL=800
TERRAIN_MAX_AUTOGEN_BUILDINGS_PER_CELL=1500
Also, in the settings in the simulator be sure to turn OFF ground shadows, lense flare and bloom effects - they are hogs on performance and I don't even notice them not there now
Tweaks for FSX performance
Tweaks for FSX performance
Command Captain Chris Saunders
SAX 411
SAX 411