Glad you like it!
I would say that when you Draw in normal Speed you feel 0 lag. When you do fast crosshatching it depends on how big your Brust size is. If you go for fine lines it felt pretty good. The bigger the brush size the more lag you will see. But this is true also for normal non-cintiq tablets. I saw some YouTube-videos where people did slow-motion recordings to analize the lagging. In those videos you can clearly see that some lag is always there.. but to be honest.. this is the first tablet PC I tested where it is so minimal that it does not bother me. It is a huge jump compared to a surface pro 3 for example.