Wow just wow.
So I enabled Shadowplay on my laptop and it blew me away. There was absolutely no fps loss when recording, even on an older game that is not in any way 'optimized' for Shadowplay.
In fact I have some footage so you can see the relatively good YouTube quality: http://www.youtube.com/watch?v=RXCkIaVxlDY
If you don't know how to do this it's extremely simple:
1.) Create a Geforce Experience shortcut and place it wherever you want.
2.) Right click on the shortcut and click 'Properties'
3.) Underneath the 'Shotcut' tab find the line labeled 'Target'
4.) Insert '-shadowplay -gamestream' after the file path.
5.) Congratulations, your shortcut now goes directly to Nvidia Shadowplay.