I updated to Ermine, and I can't replicate this bug. But what I mean is, I can't replicate the lag in drawing. So I can't say conclusively whether the "catch up" is really there or not, because I haven't yet had my machine need to "catch up" to my writing.

I do notice something I'd noticed both just before I updated and now after updating (so it's not Ermine's fault) that hadn't happened before: sometimes my very last pencil stroke is "invisible" until I either refresh, save or draw another stroke. So for example, if you cross a t as your final action, you won't see the t cross, but it's there. It doesn't happen consistently, but it's been happening a noticeable amount. Started just a couple of days before I upgraded, and is still happening.

I haven't tried recalibrating yet, which I know I should. If that fixes the problem, I'll report back. (Why do I never think of the obvious thing to try until I'm already in the middle of a post?!)