If your home directory is NFS-mounted from an NFS server that believes in the NFS v2 specification and so doesn't acknowledge actions until they've been written to disk, starting up the Gnome panel program as part of logging in is achingly slow, taking 30, 60, or more seconds. This is caused by a small programming bug in the panel code. The gnome bug report (and accompanying patch) is at the cited URL, http://bugs.gnome.org/db/38/3844.html
The fix appears to have been applied in the Gnome CVS tree, so this bug can probably be marked RESOLVED unless you want to build a version of October Gnome with this patch included by hand.