Just had a quick look at Plusnet's page with a handy tool, and it took 12 seconds to load their 1.25 Meg front page. It starts with a 301 (moved) redirect, and on to the main page itself, which takes 4 seconds to load. Then there's twenty six 404 responses which account for a total of 23 seconds (responding concurrently, not consecutively) of latency.
Plusnet - 12.2 sec ~ 1.26 Meg ~ 97 requests ~ 0.103 speed
Zen - 7.6 sec ~ 3.17 Meg ~ 62 requests ~ 0.417 speed
IDNet - 2.2 sec ~ 0.8 Meg ~ 43 requests ~ 0.363 speed
BTBroadband - 7.7 sec ~ 2.6 Meg ~ 81 requests ~ 0.337 speed
(speed is Meg divided by seconds - 1 Meg in 1 second would result in score of 1)