vB4, which is the software this site runs on, is slow loading.
It's been the bain of my life since April. Compared with vB3, average page size has well over doubled, meaning even on fast internet connections, simple pages can take a couple of seconds to load, and if you've not got a fast computer, the huge amount of scripting and CSS can take a while for some browsers to load/interpret/display.

For example, this page needed 806KB of information to display. Which breaks down into 108KB of documents, 277KB of images, 291KB of scripting, and 114KB of CSS files.
A similar page in vB3 would be about 3-400KB.