Is there a way to speed up the animation time for switching between spaces? (Or maybe turning them off?). Preferably without buying a third party app. Maybe there's an option defaults.
I'm on Sierra 10.12.6.
This looks like a duplicate of Speed up Mission Control animations in macOS Sierra
Here's the short answer. If you want extremely fast animations, this is your defaults write command:
defaults write com.apple.dock expose-animation-duration -float 0.1