Kevin Fenzi just commented on
https://bugzilla.redhat.com/show_bug.cgi?id=487757
that it might be related to
https://bugzilla.redhat.com/show_bug.cgi?id=490839
and enabling Compiz "fixes" the latter.
And indeed, enabling Desktop Effects does indeed make
(the installed) emacs 22.3 quite zippy again!
--
--Per Bothner
per(a)bothner.com
http://per.bothner.com/