4.4 should be a good boost to your setup, by default it will switch to file based session handler, so if you're on some kind of cluster setup you'll need to make it use db session handler preferably before you upgrade (so it uses when the new code starts to run).
thanks for your reply, unfortunately I didn't manage to upgrade cleanly, after the upgrade I had got some pretty big SQL errors about non-existent field (even with SQL upgrade done) so I reverted to 4.3.
I'm not in cluster mode so file based session should be just fine for my setup. I will give another shot at the upgrade but for now I can't afford to pass too many time on it.