IDE slow to respond to key clicks Windows 7

Since the last windows update, the Arduino IDE hangs for several seconds when clicking any button - e.g. Upload, Verify, Save and close window. Has anyone else seen this or is it my P.C.? Using IDE v 1.6.10.

Virus scanner interfering? It might want to scan all related files before allowing e.g. the compiler to run? You can switch it off for testing purposes.

Which version of the IDE?

So after a lot of messing about, it turns that the IDE v1.6.10 takes "ages" to update/save the source file, so any operation which requires source update/save also suffered from the same delay (up to 1 minute) . Removed Arduino IDE completely from windows, and re-installed 1.6.5r2. Now back to normal response times.