Right, a bit more research - from someone on Usenet:
that "comformant opengl texture clamp behavior" has something to do with the way the graphics are drawn onto your screen, some textures are drawn outside of the viewable screen, "over the edge" and clamp behavior clamps those textures right to the border of your monitor letting none escape.
It's probably interpolating between vertices to create vertices on the screen boundary, then interpolating the texture coords to make the new vertex texture correctly. Nothing that shouldn't be done lightning fast in hardware, I'd have thought?
Well, whatever. It's the kind of thing that you shouldn't worry about at all
. You as the developer have no way of knowing
what the effect of that setting is on the performance of the application! Just because your system with an MX440 on those particular drivers has a bad time of it, doesn't mean any other system will suffer. Hopefully anyone who messes with the driver's OpenGL settings and notices a slowdown like that will have the good sense to click "Restore Factory Settings" and learn to leave things alone unless they know what they're doing.