Very long topic history.dat DoS Mozilla will log various bits of URL information into the history.dat file. A VERY long title logged to the history.dat file will cause Mozilla to startup very slows and eat a great deal of memory. This behavior will persist until the history information is cleared. https://bugzilla.mozilla.org/show_bug.cgi?id=319004
From User-Agent: XML-RPC mozilla-1.7.12-1.5.2 has been pushed for FC4, which should resolve this issue. If these problems are still present in this version, then please make note of it in this bug report.
Closing this bug CURRENTRELEASE. Update announcement FEDORA-2006-075 for this issue is at: http://www.redhat.com/archives/fedora-announce-list/2006-February/msg00005.html