On my P4 1.7ghz W2K box with 512mg of RAM, the default JBoss target starts in about 1 minute. The All target is slightly longer because it deploys more services then default does.
This, of course, will change as you add or take away services from your own custom target.
You should go through conf/jboss-service.xml and the contents of the deploy directory to make sure you're only deploying components that you're going to use - it takes a while to work out what everything is and there's still some bits I'm unclear about (I just know we don't use them!).
3.2.2 takes 2-3 minutes to start up on one of our Sun servers, but that's not really an indication of how well it runs JBoss. It's an 8 processor system but none of the processors are particularly fast.
The start up is single threaded (at least it seems to be), so multi processor systems don't benefit until it's serving requests.
We're upgrading to 3.2.3 and using a newer version of xercesImpl.jar, and it now starts in about 1:30.
We tested an earlier version of JBoss 3.x on a dual processor linux box (2 x 2GHz), and it started in 40 seconds but it couldn't handle the same load as the Sun box.
Hmmm....I have JBoss 3.2.2 configured to run the "all" configuration with some additional components that I have written. This configuration starts in 1 minute or less on every platform that I am using (Win2K P4 1.8GHz desktop development system w/ 256MB RAM, Win2K P3 1Ghz w/ 512MB RAM, and HP/UX 11.00 dual processor server w/ 1GB RAM). You might want to check to see if there is a bottleneck in your connections to other servers (e.g., database) or if the JBoss server is running other processes that are hogging the CPU cycles.
I should also check how much logging you are doing. Having your all your loggers set to TRACE level can cause a log file to grow to 10MB on startup and take ages. I know, I tried :)