As I’ve said many times, Emacs is the first thing I start after a boot and it stays running until the next boot or I update packages that need a restart. That means that Emacs startup time is a non-issue for me. If you’re one of those people who like to start Emacs when you need it and shut it down afterwards, Emacs can be painfully slow to get running. Fortunately, Emacs has you covered. You can start Emacs in server mode and use emacsclient to bring up a frame whenever you need one.
Sadly, it’s hard to start a GUI Emacs frame without going through the terminal first. Dante Catalfamo has a handy post that discusses his method of starting GUI frames with emacsclient. He uses iCanHazShortcut to map hotkeys to actions that would otherwise require invocation on the command line. I’ve always used Alfred or Quicksilver for things like that but iCanHazShortcut seems like a nice lightweight solution if you don’t want or need the power of Alfred or Quicksilver. Really, macOS should have the hotkey capabilities built in but the above utilities are free and more than capable.
In any event, if you’re an Emacs user on macOS, you should take a look at Catalfamo’s post. It’s a short and easy read.