I think I reported this once before, but the problem still exists. I checked other bug reports that talk about the slowness. They say they have been resolved, but this problem has not.
Long pages on the English Wikipedia that have a lot of links such as [[List of chess books, A-L]] usually take 30-35 seconds to load. A couple examples from today:
<!-- Served by srv137 in 34.009 secs. -->
<!-- Served by srv201 in 31.683 secs. -->
Before when I was discussing this problem (probably about three months ago), there was something missing dealing with cache in the downloaded file (I forgot what).
If the page has NOT changed and I am NOT logged in, it is fast. Otherwise it is slow. People were suspecting something in my Preferences is causing it, perhaps a gadget. I don't use many gadgets except Twinkle.
I've tested it under IE, Firefox, and Chrome. Chrome works the best - it seems to be fast if the page has not changed, even if I am logged in. The others are slow anytime I'm logged in, and the page has changed.