Fart Guardian

I have an ATI HD 4800 and I have had this problem too, for the last few months. Despite running smoothly on ultra high graphics for many months beforehand, now on the ABSOLUTE LOWEST graphics the client lags so severely it's unusable. It's like one frame per 10 seconds. I'm updating my drivers as I am posting this, hoping it will work... there have been ATI specific issues with SL in the past (before this, it was sharp holes in the clouds and some other textures).