Re: bbPress loading slower than site.
I think you first need to determine how long bbPress is actually taking to generate a page, and how long it takes to generate the other pages on the site. You can start with _ck_’s mini-stats plugin for bbPress.
[edit: see johnhiler’s link below to the bb-benchmark plugin]
And, on the other part of your site, what is running that? Is it WordPress or just static HTML? If it’s WordPress, you can get a plugin as well to point out performance bottlenecks.
Regardless of what type of software a site (your site) is running, there are lots of tools you can run in your browser to find performance bottlenecks.
Firefox (you need that to run most of these add-ons)
Firebug (all around awesome tool)
There are tons and tons of performance add-ons for Firefox but these will get the job done.
Also, what host are you on, and can you post the URL here so others may see the performance first hand?