I've done a simple test with my Macbook Air, using the app "Is It Snappy", as mentioned in the comments. I used the keyboard on my macbook, which is a chiclet style mechanism. The tests were all done in triplicate except for TextEdit, (only twice)

TextEdit: ~81 ms from key depression to when LCD pixels begin to shift. For Sublime Text: ~86 ms. Both of these text editors are pretty well matched.

However, if you boot into Recovery Mode in macOS, you gain access to a GUI without a V-synced/tripled framebuffer. Terminal in Recovery Mode: ~57 ms

Finally, the kicker. macOS users have always had access to a terminal interface upon boot called single-user mode:

Single User Mode: 37.5ms (all three measurements were the same)

If you want to experience what the latency on old computers felt like while typing, simply reboot your mac, and while it's starting up, hold 'Command + S'!