It might be that dns queries take a while. Do you have a local dns caching server?
Have a look at /etc/resolv.conf
Pay attention to the nameserver line(s)
If you have
Code:
nameserver 127.0.0.1
You are using a dns caching nameserver (faster)
If not, every time you load a page, there are several dns queries to find the site's IP.
Windows uses automatic caching.
P.S. Using gnome or kde shouldn't change anything.