AFAIR, the full build was also around 30 minutes on a desktop i7. Unfortunately, incremental build (even for the most tiny changes) was around 2-3 minutes which was a real killer for me when I tried to do some open source work on it.
There are tricks to make it faster. If you find yourself working on the project again, ask for advice on IRC. 2-3 minutes is longer than it should take in most cases. (As long as you aren't touching widely included headers files, that is.)
yup. 30ish for a full compile, less with ccache and other tricks. Rebuilds 2-3 minutes.