The new workbench save feature  introduces a slow memory leak, which can show up if eclipse is left running over the weekend (sometimes even overnight).Â This has been fixed in master  and there is a workaround for M6:
Go to Preferences > General and set the Workbench save interval to 0 (that will disable the auto-save job).
 BugÂ2369 -[Workbench] Would like to be able to save workspace without exiting
 BugÂ402912 -OutOfMemoryError when eclipse left overnight
-- Paul Webster Hi floor.Â Make me a sammich! - GIR