On a serious note, regarding the "slow" speed of UI response, I think stefcep2 has totally overlooked the important point that a lot of it is deliberate.
He might want menus and the like to instantly flicker in and out of view as he's skimming his mouse through them but most ordinary users are disturbed by it. Consequently, delays are built into a lot of UI systems for the benefit of the end user.
As a worked example, gnome is no different. When you access the menus, there is a delay before each sub menu opens. Is this because the design is "sh*t", badly coded and in desperate need of optimization? No.
If you don't believe me, try editing (or creating if it doesn't already exist) your ~/.gtkrc-2.0 configuration file and changing/adding as appropriate the following:
gtk-menu-popup-delay = 0
Then restart gnome...