Reported by customer at https://support.atlassian.com/browse/FSH-926
If you have a changeset with large number of changes (usually a svn copy or move), e.g. https://extranet.atlassian.com/crucible/changelog/FE/branches/iteration03?cs=7765 which could have potentially hundred of thousands of changes, fisheye will keep they in memory as an arraylist of RevInfoKey which eats of memory.
This can cause out of memory errors.
If you need to inspect a heap dump for more details refer to case above.