Pen Lag? My tablet has just recently had issues with sensitivity. no matter how close the pen is to the tablet the pointer doesn't recognize it until I'm actually touching it. which is problematic if I just want to move across the screen. then on the rare occasion that it does the pointer's movements are choppy and not precise at all. like its skipping or something. Help would be greatly appreciated!

I had a serious lag issue with Genius Easypen F610E. You draw a square but the signal is laggy and it is unable to draw it properly. Leaves even a trace behind (see pic below with black squares). Searched the internet for solutions, it seems some others have the same issue.
Changing battery didnt help. Changing computer and OS didnt help. But its an issue of electrostatics (pen, tablet, your body) as I noticed. I needed to wrap a foil around the pen's upper part, and connect it to battery's minus terminal. That fixed the lag problem. Its not pretty, but it works.(see green squares in the picture).
It's seems to be a design flaw.

It MAY be that your battery in the pen is running out of power.