If you have Ati video card and you are using proprietary drivers than you may notice delay/lag when you are maximizing applications or any window.
This can become very annoying.
To fix this go to terminal and type:
(I have been using k0ekk0ek's PPA fror long time, but sinc last X update it don't help)
sudo add-apt-repository ppa:k0ekk0ek/ppa
sudo add-apt-repository ppa:info-g-com/xserver-xorg-1.7.6-gc
sudo apt-get update
wait until it finish
sudo apt-get upgrade
Restart X server (restart computer or log out) and you done.