I know, that title isn't exactly technical, but it can be hard to describe succinctly.
I have noticed a lot of jumpiness in the script debugger. I'll be stepping through a script and as it transitions between steps the scroll-point of the debugger will jump to the top, the lower portion of the debugger-script-area window goes blank (almost like it's switched to a new script; not the Stack portion going blank, but the main window containing script steps), and then it switches back - the scroll-point jumps back to where it was and then the window fills in with all the current script steps again.
It's like watching a screen re-draw in slow motion or something. Quite noticeable and very distracting, though. I don't have any screen caps or recordings of this one, though. I don't know how to reproduce it, either.