Alright you guys with Blackberry's....
If you can get to the "Go to" page on the browser, and it's taking forever from there, clear your cache and history. To do that, make sure you're on the "Go to" page, hit the menu key (Button with all the dots), select "Options", select "Cache Operations", clear it all.
If it's just RIU that's giving you issues....
Go into "Options" (The sane place Cache Operations is in), Select "Browser Configuration", and make sure all boxes are checked. Make sure show images says On WML & HTML, same with Content Mode.
Also when on the home screen, hold down ALT and press, L, G, L, G, when you're in the Event Log, press the Menu key (Button with dots) and select Clear Log, the select Delete. (This helps improve/maintain all around performance on BlackBerry's not just browser performance)
If none of this works then you need to pull your battery, or it's network related.
Hope this helps