In Eclipse Juno SR1 on OSX 10.8.2 Mountain Lion, Java version "1.6.0_37", a while after startup it becomes very slow to simply switch between tabs for source files being edited. The CPU goes to 100% and the editor freezes for several seconds before the new tab content is shown.
Upon reading about the problem I edited my eclipse.ini to have:
--launcher.XXMaxPermSize 2768M
-XX:MaxPermSize=2768M
-Xms440m
-Xmx2512m
As advised at http://wiki.eclipse.org/, and this only had the effect that now it takes longer after I restart Eclipse for the problem to start happening again.
I can't believe that on a machine with a SATAIII SSD, an i5 processor and 8GB of ram that switching tabs in a text editor could be so slow. Is there anything else I can try?