Graphics can't keep up with system speed

[Kelainefes]

Originally Posted by WILSON

From what ive read FSX likes more cpu that gpu but powerfull cards are always a bonus and you should cap you max fps to about 30 or so as no higher is needed for it to run smooth.

It's true that FSX is very CPU hungry, but I have to disagree on the other point you make.
The human eye can spot the difference up to about 60 FPS.
In a movie 24, 25 or 29.97 FPS are ok because of the motion blur present in the picture, but in a videogame every frame is rendered as if it were shot by a camera with infinitely short exposure time, therefore there is no motion blur.
This is most evident when something moves fast, in instance in a first person shooter type of game. Maybe it is less evident in FSX, but it is still there and up to about 60 FPS there is a difference.

[WILSON]

Yes i totally agree with you and i think FSX is the only game that is capped at 20 fps at default by microsoft but 30 seems to be the sweet spot for most people. Not sure why they have it so low but it does run ok and all i can guess is that its because your moveing slow and don`t need hight fps like you do in say cod5.

[Kelainefes]

Well, it's true that the slower the movement the more difficult it is to spot the jerkinesses in the movement.