I cannot move, scale or rotate a cloned subtool normally. I have to drag it 20 times to move it incrimentally. I have 8 subtools total and I’ve turned off 5 of them in case it was a memory issue. The entire model is just over 49.394 mil. and the tool I’m trying to move has a 295,545 active points count. I assume that my subtool is too big as it’s made from a alpha extrusion of an image plane…Any ideas???
Out of curiosity, how large is the model relative to the Tool>Preview window?
Also, which version of ZBrush are you using? That kind of makes a difference when it comes to trying to help. ;)
ZB3.2 MAC
Here is a pic of the model and preview box. I’m trying to clone the tooth and finish off the rows of teeth. 
I think the problem is that you have so many polygons visible, PLUS polyframe at a high mesh density (lots of lines needing to be drawn), PLUS polypaint. Try turning off the polyframe and if that doesn’t do enough hide the SubTools you don’t really need for the step you’re working on.
Tried everything you said but absolutely no effect. DRAT. Hmmmm