Having a custom spring config that disables services you don't need to start (maybe FTP, CIFS etc.) will help. Upgrading disk and CPU will help (changing from my PentiumM laptop to a new Core2 laptop + good laptop HD really helped). Also launching the server using java6 is faster than java5 - but note you can't currently compile Alfresco using the javac.exe from java6.
Tomcat is the fastest container to stop/start. JBoss is slower.
Thanks,
Kevin