Comment by colechristensen

Yup, that's how long it takes. There are a bunch of competing requirements and 9 minutes to orbit is the sweet spot, you can't change it much in either direction. If you go slower you waste all of your fuel just holding yourself up against gravity ("gravity drag" which is a bit of a tongue in cheek engineering term) If you go much faster you're accelerating too hard for your passengers or your structure.

To understand gravity drag think about the rocket firing just hard enough to hover 1 meter above the pad, you burn out all your fuel in 10 or 15 minutes and go nowhere...

In the other direction if you want to accelerate harder you need to make your structure stronger so you need to burn more fuel per second and have to displace some fuel in exchange for more structure and you keep doing that until you're so heavy you can't produce any more acceleration and you're all engine and structure and no fuel.