So normal boot time is about 30ish seconds, with another small period of time until the map databases are fully loaded (I think it's under 30 seconds, but don't remember off the top of my head).
Now, if you've just loaded a high resolution terrain database, the NEXT boot only can take up to two minutes before you're looking at the main PFD/MAP/EMS SkyView screen.
All that said, what version of software are you on? We know that a few people are experiencing longer boots than they deserve after upgrading to 11.1, and we're currently looking into that. Does holding button 8 (the last button) while you boot change anything?