Uncheck "use smart CPU usage reduction", restart UO and razor and then see the difference. When you log back in, try moving items around in your bag as if organizing. You'll notice it's smoother and lacks the "cursor lagg" that you may have if it's checked. You may also notice your character can turn smoother and overall the gameplay feels smoother and less "laggy" or "choppy".
Here's a screenshot to show you what option I'm talking about:

Remember after unchecking this option you must restart UO and razor. Then log back and and notice how smooth it is overall = )
It may be subtle or a big difference but everyone who has unchecked it agrees with me that the game is more smooth, enjoyable and most importantly era accurate overall!