I recently put Mint in place of OS X on my macbook and loved it but the mouse seemed laggy and everything responded slowly. I was digging the Cinnamon DE but just switched to XFCE and I'm loving it. I knew it was lighter and sure enough everything runs smooth as butter on this old macbook. Funny thing is I never liked the screenshots of XFCE, but I guess I just had to see it in person. Kind of reminds me of BeOS a little.... and yes I've tried the new Haiku OS lol.