>>18
KDE and Gnome both take a lot of memory. XFCE, ion and some other DMs are faster but offer less functionnalities (well, ion offers close to no functionnality at all).
If you think your comp is powerful enough to handle it, then maybe the problem is not KDE.
>>16
That's because Windows loads its graphic libraries when starting. KDE programs start faster on KDE, but launching a GTK-based program takes a while.
Same thing under windows : launching the Gimp takes more time cause you need to load GTK.
I'm not saying Linux doesn't suffer from said /lib problems, but Windows only hides the problem, it doesn't resolve it.