not at work- so can't check exact settings- but uncheck the box to scan compressed /or zip files in on-access scanner. Java files are seen as compressed so if you uncheck this then it should improve performance for java apps.
Normal compressed files such as cabs etc should scan once expanded so you don't lose any functionality.
here's the KB id:
Slow performance with Java-based applications
Corporate KnowledgeBase ID: KB58727
it actually just ended up being scriptscan. once I disabled that it was all good.