I just had SP2 installed and found to my dismay the detrimental effect on FS9 performance. Somebody suggested DEP (see my thread on SP2 forum if you dont know what DEP is all about). I played with that and the frame rates that I saw with DEP on and off didn't suggest it is DEP as the cause of the performance downgrade.I then turned on the CPU monitor while FS9 is running. Surprise, surprise, FS9 is using about 50% CPU. The rest is system idle!! Does it mean IO as the bottleneck? But what IO?? I was sitting in Meig 36 and enjoying the scenery from the cabin in the Cessana! The plane is not flying and no scenery to change and IO from disk.Does it mean video bandwidth? I overclock my P4 2.4C to 3.0 and run the FSB at 800! What else could it be? :( Michael TanYSCB

I would guess you have a HT enabled CPU, if so, 50% in the task manager is perfectly normal, it does not mean FS9 is ONLY using 50% of your CPU, it means that it is only using 1 virtual processor as FS does not support multi-threading.How bad a performance drop are we talking about?Dan.

I'd try reinstalling all the drivers. Including the chipset drivers.MK

DanYou are right. My CPU is HT-enabled.Before SP2, I used to get 50-60 fps. Now I am getting 30-40 fps for the same spot.Would disable HT make any difference?M TanYSCB

I have only found HT is a problem with the Garmin GNS530 from Reality XP, in other circumstances it makes no difference either way.That said, there is a patch available that can turn off HT for FS permanantly, I have not used it myself. http://home.comcast.net/~gulfstream-v/index.htmlTry reinstalling all the latest drivers, and make sure that there are no CPU hungry apps running when you are running FS.Dan.