Can somebody clear this up for me please? I always thought LXDE comes without a compositor or an element that is present in other desktop environments (DE's) that causes other desktop environments to degrade desktop performance. If it was the case, LXDE would beat any DE in terms of gaming performance in any test but it doesn't seem to be the case - see http://www.phoronix.com/scan.php?page=article&item=ubuntu_1210beta_desktops&num=1
The tests were conducted by "Frames per second - More is better" and LXDE beats most of the DE's, aside from certain situations (sometimes XFCE beat it, also a lightweight option), and -
Which gave KDE quite an advantage.
This article does confirm that you made a way better choice than Unity, as: