I have has flight sim X for ages now and I recantly got some add on planes to fly.
Normally when i load up a 737 is works fine no lagg or slowness
But for somes planes like the 727 addon, the game suddenly becomes really slow and laggy and i dont know whats wrong.
It happens for some other add on planes too
Never happens for the default ones..
I have A ATI Radeon HD card
And I Know I Have 4GB Ram
I Can get my full specs if needed