As ridiculous as that sounds, if you want a very responsive user interface because you are more interested in getting work done than looking at XP's Fisher-Price graphics, then turning off themes and visual effects has got to be the best idea since sliced cheese spread. You might not like what you see, but it will be faster.
You can disable all of XPs visual effects by right-clicking the Desktop and selecting the "Properties" menu item, select the "Appearance" tab. In the dropdown box under "Windows and buttons", choose Windows Classic style.
