Comment 17 for bug 1037411

I call glCopyPixels a couple of times briefly on startup and then never again. The problem is that doing this makes all subsequent rendering much slower. If I never call glCopyPixels on startup then rendering remains fast thereafter.

It seems glCopyPixels is modifying the context in a way that permanently cripples later operations. The only possible cause I can see so far is:

src/mesa/main/drawpix.c: _mesa_CopyPixels:
   /* We're not using the current vertex program, and the driver may install
    * it's own. Note: this may dirty some state.
    */
   _mesa_set_vp_override(ctx, GL_TRUE);

This seems to set a flag in the ctx which is never cleared.

Using Mesa 8.0.2 in Ubuntu 12.04