I think `-c` skips loading configuration. Launching a prompt will be much slower. In fish almost everything is a function and functions are loaded lazily.

Might be an OS X thing. At work on Debian zsh starts up instantly, at home on OS X it takes a good couple of seconds.

It's an oh-my-zsh thing, mostly. Turns out that running a lot of scripts on startup makes startup take a while.

Thing is in fish functions and completions load lazily as needed, and basically every customization is done with functions. Startup is pretty much instant regardless of configuration.

I don't run omz or many scripts for my zsh configuration.

Might want to check this out:

https://news.ycombinator.com/item?id=3880280

path_helper turned out to be boning me pretty hard at home, these instructions were very helpful.