Application, improve performance of touch events
This seems to be a bug. Take a look at this post.
Or
http://www.codeproject.com/Articles/692286/WPF-and-multi-touch
it's hard to say why you have such an issue - may be OnTouchMove is triggered more often than MouseMove and you should create some additional processing to smooth the touch positions data.I'd try to comment all the code under the Point currentPosition = e.GetTouchPoint(this).Position;
and look at the performance.
Another approach is to count how much OnTouchMove is triggered.
The problem is the touch device, try another one to see if the lag is still there.