I recommend starting out with a blank emacs and then digging through this repo for useful snippets, instead of using it directly. I have heavily configured my emacs, many default bindings have changed, and behaviour has changed for many packages to better fit the way I work.
It should however be possible to simply clone the entire repo, drop it into a clean install of emacs, and it should set everything up properly, that's how I use it when I need to get something done on a new machine.
I usually rebuild emacs from master once a month, so some things will probably not work on older emacsen.
Most configuration takes place in init.el, it tries to be concise, but have enough comments
to make it easy to grok.
I run emacs using the daemon, so start-up time is not a big concern, this config usually starts within 2-6 seconds. I very rarely start emacs from cold, I do however want the config to be snappy, and I go out of my way to try and improve performance for common tasks.