If it takes a second, then it sounds that the screens don't fit into the graphics memory, and they must be swapped between RAM and VMEM when you switch between them. Probably triplebuffering and enhanced mode screens consume too much memory to fit in the gfx mem on your setup.

When I have the FullHD enhanced mode Ambient + other non-enhanced FullHD screens (which consume wayy less memory than enhanced/buffered screens), switching between screens take only fraction of a second... it's immediate and you can't say it would take any time in human eyes. This is because there's enough graphics memory to store them all.

Maybe your 9800 PRO has more graphics memory and it's faster because of that (all screens fit into the graphics card's mem)?