We work for the MOD and we cannot change networks, we have what we are told. So changing network settings etc is impossible. Its virtually impossible to find out what is set!
Just rolled back our testsite to V5.3 and the speed difference is incredible. V5.3 zooms so fast its like a dream!
But our main problem is that V5.3 is no longer supported and V6 has a load of fixes in that makes rolling back very undesirable.
I shall be setting up a Virtual PC at home and will test IE6 from there, just dont like wasting time at home working ;-)