GUI freezes periodically

[GoogleCodeExporter]

It seems that there is some background task that is performed periodically that 
blocks the GUI. The application is still usable because keystrokes are buffered 
anyway. The issue is more related to the comfort of seeing what you are typing 
in realtime.

I haven't checked the source code, but from my experience this issue could be 
maybe handled with moving the blocking task to a background thread to keep the 
GUI always responsive.

Thanks for this great software!

Original issue reported on code.google.com by [email protected] on 29 Mar 2013 at 8:15