I have access to IE6, IE7, IE8 and FF2 at the moment.
The fastest browser to load and do useful stuff with is IE6.
This is reasonably fair comparison, as they are running on similar PCs.
I'm not saying that IE6 is secure or functionally rich (I miss tabs) - just faster.
But then I have plug-ins installed on all the others which are probably slowing them down.
Slowest to load is IE7, with IEPro.
SD