New requirements in Cataclysm?

[Zub]

Hi all,
I used to 5 box in Wotlk using 2 machines: 1 account on my main machine and 4 on my second.
I also remember still playing 5 toons (gnome team) in the early weeks of wow 4.0.

I've stopped playing since, but just created 3 trial accounts and started them on my second machine, and the performace is now really bad. It was never perfect (couldnt go in towns with all toons together for example) but it worked.
Now, i can't even play it because the performance is so low.

I've noticed that there has been some changess in the WoW video options. For example the directX dropdown (only shows 9 in my case) and the fact that we can't fully disable shadows.
I've set all video setting to 'low' but with no success.

i tried with set fps to 30/10 and 20/20 but with no visible change

The machine is an old Duo CPU E7300 @2.66GHz with 2Gb, but before you say anything, it used to run 4 on TBC/Wotlk.
now it can't run 3

Any suggestions?
Upgrade is a no-no at the moment. Just want to know what i can tweak or install to help.

Cheers,
Zub