Apple - Disable animation for "Swipe between full-screen apps"?

Sys Pref > Reduce motion

You can replace the horizontal sliding screen effect with a gentle fade-in, where one screen translucently covers and replaces the other. Works on macOS Sierra 10.12.6.

A faster/slower swipe of your fingers make a faster/slower fade-in. You can even stop mid-swipe to show the other screen translucently covering the present screen.

Choose System Preferences > Accessibility > Display > Reduce motion.