You can also experiment with angling the camera inside the city....in certain directions the graphics slowdown goes away. Something inside the city apparently causes the slowdown, but I can't work out what.
Shader Model 2....
Nah, it's not that - i've been running since day one with 'force dx9 shaders' on (that's shader model 3 fyi) and i still get it.

The fixes look impressive, though i am annoyed that they missed the 2 handed weapon bug.

I just wish we didn't have such slow internet in australia :(