Since I upgraded my project to Scala 2.8, I find that those horrible pauses that interrupt everything have returned. And some of them happen even when no modification has been made to the file being edited (e.g, when opening the "Find in Path..." dialog or when a rename refactoring is initiated (even one for a local variable).
I'm not sure why switching to 2.8 would cause this, but it's extremely frustrating and I hope it can be addressed soon.
IDEA: 9.0.1 #IU-93.94
Java: Sun JDK 1.6.0_u17
OS: Linux 2.6.27
arch: x86 (32 bits)