Sorry I didn't realise I wasn't subscribed to this bug - sorry it's taken me so long to reply.
I uninstalled the Compiz PPA and now I'm using version unity version 4.24.0-0ubuntu2.1vv1 and Compiz 1:0.9.6+bzr20110929-0ubuntu6. It seems to better - at least it's usable - but I still think it's not as smooth as it was when I was running Natty.
Sorry I didn't realise I wasn't subscribed to this bug - sorry it's taken me so long to reply.
I uninstalled the Compiz PPA and now I'm using version unity version 4.24.0- 0ubuntu2. 1vv1 and Compiz 1:0.9.6+ bzr20110929- 0ubuntu6. It seems to better - at least it's usable - but I still think it's not as smooth as it was when I was running Natty.