DF was also slowing my system down a lot. Upon playing around with some of the settings, I turned off the 'Allow DisplayFusion to manage the screen saver' and the system perked right back up.
So I then turned it back on and the system is still perky.
Is it possible that somehow the screensaver management section of DF was reset when I did that?
Weird, it should maintain your settings when checking/unchecking the "Allow DisplayFusion to manage the Screen Saver" box. If it happens again, let us know.
Thanks!