Thanks for looking into this, the progress is quite visible in 2072.
2061 allowed me to easily open one of the biggest fears in my current project (the previously mentioned 8000 lines class, that got to 11700 lately), while 2072 is handling editing, too, without any annoying delays (not in all cases, though, see below).
The complete error check finished after about 5 minutes, but I couldn't care less about it at this point. I can edit the file, the moment I move the cursor on a line the syntax colouring is applied in a few seconds to that line and a couple of screens around it (nice touch here, btw), scrolling is smooth, the structure view stays in sync with the editor without delays.
I haven't tried refactoring yet (coming soon), but I hope for the best.
The only delay I still notice at this point is when typing AFTER the code analysis has been completed. For some reason, IDEA seems to treat the partial code analysis differently, and the editor freezes until it's complete. If you could align the performance there with the one we get for the initial analysis, things would be almost perfect again. :)