You could try running a local caching proxy. If you were on Linux or other *nix variants, I'd suggest Squid. However I assume you're on Windows, and I don't have any good suggestion there other than google for "windows caching proxy" (the standard go-to proxy for Windows is usually Privoxy, but that's for filtering out ads and stuff and is
not a caching proxy). By using a caching proxy, any images, scripts, stylesheets, etc that have not changed since the last time you visited will already be available locally and you'll avoid having to download them all over again. You won't notice an immediate speed improvement as you have to prime the cache, but once you've browsed a few
threads and gone
through your normal browsing routine, future browsing will be much, much faster.
I'd also suggest using Firefox and running the AdBlock Plus extension. Only Firefox allows plugins the ability to block downloads
before they start (recent updates to Chrome allow this as well, but there's no adblocker yet for Chrome that uses this ability). This means that you won't spend precious bandwidth pulling down ads because ABP will catch and block them before they're downloaded.