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.

You can control the animation speed by not swiping your fingers as fast. The actual code is quite tightly coupled into the OS and there's been no signs of people finding a hidden setting to speed up or even change the animations.

You could also use mission control to have the screen animation come down from above if the nausea is caused by left-right visual motion.

Lastly, if you really need to control the motion, you might have to pre-record the screen and just speak to it. Keynote and editing the video would allow you to fade to black or use another transition idiom than a wipe.