If the server has been tweaked inefficiently or set up wrong, that could do it. Plugins can do it. There’s too many variables it could be without :
a) looking myself 
b) knowing what’s on there.
I looked at your site and three things right off the top;
1). Ditch the Get Satisfaction button and link to them. That code for their widget is terrible AND it will definitely slow down your site. I think you should also think about the other social bookmark widget too. I would also add that there are time when the Facebook Fan widget loads really slowly. Better yet just take all of those off then see if your site loads faster. Bottom line keep the JavaScript widgets to a minimum.
2). Add this to the top of your .htaccess file;
AddType x-mapp-php5 .php
AddHandler x-mapp-php5 .php
3). If 2 worked add this to the top of your header.php
?php
ini_set(‘zlib.output_compression’, ‘On’);
ini_set(‘zlib.output_compression_level’, ‘1’);
?
(of course ad the <> )
Try all three of those things and see how much faster you are loading… Andrea is right next time add a link to your site if you want help.
Seems to be way better after I bought more ram!
The site and my other site ti was just too much!
Now I’m running 2 gigs of ram!
What is this supposed to do?
2). Add this to the top of your .htaccess file;
AddType x-mapp-php5 .php
AddHandler x-mapp-php5 .php
I tried it. It just kills my site, white page. Does it depend on the server configuration?
Yeah, if you have php5. If not, I can see it borking.
I have an inexpensive dedicated box at http://iweb.com/ with… I think 2 GB of RAM and a 3GHz Athlon CPU… and even without eAccelerator installed or zlib enabled at the moment… BP+WPMU screams. So… as they say… YMMV.
I usually tell people for an active site, minimum 512 megs of ram.
you don’t get that on shared. 
I have a 3.0 gig processor and 2 gigs of ram.
Since I updated to the new buddy press I am running way faster!
have you tried the minify plugin. it made my site 70% faster. when checked on firebug [page loading]
