A few builds ago of Maia I switched to Java 6, when the Java update arrive. It was really fast. These are my settings:
<string>-Xms256m -Xmx1024m -XX:MaxPermSize=800m -Xbootclasspath/a:../lib/boot.jar -ea -agentlib:yjpagent=disablej2ee</string>
Since I'm using Maia M1 - 10369 the editor, even scrolling on the project view is very, very slow. Code completion also.
I switched to Java 5, but it's the same behaviour.
What can I do to solve this problem or how can I help you to do it in the next build?
Another issue is, that IDEA 9 needs about 2 times more memory to run GWT project than IDEA 8.