My OpenGL/SDL Program SlowDown

I have used sdl and opengl for two years…

And so I have had much profits from SDL…

But I have one problem…

My Program( It’s Game… ) runs on Linux at Fullscreen( 800x600x16 @60 )

It works very nice…But It suddenly slows down about five days runs…

There’s no Memory Leaks.

And the qurious thing is that without turn it off, Just switching to Console

and coming back to X, It restores its speed…Hell…

And It doesn’t happen on windows.

What’s the Matter???