Thanks Superku, had not thought of using that.

I'll have to rebuild the noise function, and store it in an array as quads need to be drawn every frame. The bitmap drawn by the quads is determined by a noise function consisting of several formulas. I can not recalculate those each frame, as that would be again very slow. When moving the screen I'll have to update the array with a column or row of new noise values from the new position then.