KDE & Xfce Don't Lead To Performance Wins Over Windows 8
With Xfce or KDE (with suspended effects), they still weren't faster than Windows 8 with its Intel Ivy Bridge graphics driver. In fact, KDE 4.10.1 was generally slower than Xfce and Unity.
There can be some performance improvements in some cases over Unity, but still not enough to surpass Windows 8.
More of the same...