Yes, it seems that whatever transformation (pixel transfer, zooming, color matrix, ...) you apply before glCopyPixels, the performance is really bad.
This suggests that these kinds of transformations are not hardware accelerated on the Quadro chip. However, an SGI Octane2 is supposed to use pretty much the same graphics hardware. But as I mentioned, the Octane2 presents much better performance.
Perhaps it's a driver issue? Maybe the Linux driver doesn't know about these transformations being accelerated and relies on a software implementation? Just a thought...
Has anyone tried this in Windows?