So, I think I've fixed it -- definitely let us know if you see that one again. I think I've also fixed the problem with characters missing strokes, so cry out if it be not so.
I'm also uploading a framerate and memory usage display, to go along with the daily practice timer. If everything's fluffy, you should be at 30 frames per second. Memory should naturally increase over time, as Flash player loads more strokes for the characters you're studying. We're mauling on our code, trying to find the cause of the eventual slowdown.