Lacking recent flash updates can cause
banners to load slowly, thus some pages too. Updating your browser regularly is essential, since revisions are often aimed at shackling those who don't 'subscribe' to the latest software versions (read spamability) at either/both ends of the connection.
Bandwidth must be shared with others on your 'branch' of the DSL(?) system, applies to cable too, and 'busy' times can clog
any part of the connection's route. (there's nothing line-of-sight about web traffic) That said, what's odd is that problems are apparent only with TBN.
I agree that browser cache, downloaded/cached pages, and security settings are the first places to look for problems, as are seldom used programs that are always launched at startup and limit 'free' RAM when they're loaded.
We usually see problems as 'the other guy's fault', but mebbe we shouldn't rule out Karma too quickly.
I'd have to try the 'Opera' browser before I could recommend it. If unencumbered, it might still lack the bling to make 'er zing.
Stay logged on (a no-brainer) and as said before, see if there's a less than ideal security setting that applies to this or other particular sites.
If you don't disconnect power between sessions, use Windows' "sleep" mode when shutting down vs committing to thrash your HDD with a full boot-up every time you start a new one. (hardware longevity issue) Op system shouldn't cause probs, only settings within yours or your browser. Good luck!