Speed problems

I programed a small game. On the most systems it works correctly.

But on some systems every OpenGL project I tested is veeeeeery slow. But Direct3D works on this systems.

Is there a way to correct this or will I have to code a second version in Direct3D ?

Things can run really really slowww when it runs of video memory.

Its more likly that you only get software rendering on certain machines.

That could be, because:

-Those machines dont have a driver that supports OpenGL (the ones that ship with windows for example)
-You are requesting a pixelformat that is not accelerated on those machines.

Without more details its really hard to tell.