Better performance

Thought I had not complained about it so far, but for very big Java source
files I encountered some slowdowns, and some hangups as well. I could not
really say what was the problem, or how to reproduce it, but on my project,
it was with big files that the hangs during error checking used to happen.
But performance on those big files seems to have been improved a lot. As far
as I can tell after an hour testing of #657.
Thanks alot for the effort you provided for fine tuning the performance.
Well done JetBrainers. You guys rock... as usual ;o)

Guillaume