I am in the process of annotating a PDF now, and though the lag has not been present, I am getting pretty bad "jigglies". In other words, I cannot draw a straight line; all of my inking is jagged, like the digitizer is getting confused. It is happening in OneNote too. In fact, this might deserve it's own thread if there is not one already. If I hold a straight edge on the screen on a diagonal, a slow trace along the edge results in pretty extreme jaggies. Horizontal and vertical seems okay. I'd post a screenshot, but I don't know how to do that easily from OneNote.but I have not had a chance to try it out since then.