What fixed it for me was disabling vsync in options.txt and setting my framerate (in options.txt) slightly higher than my monitor supports. (e.g. 60Hz monitor would be 61 - 70) That seems to have stopped the input delay.
I'm having the same problem. Delay started after update to 1.16.200. I'm using a GTX 1050 ti and i5-8300H. I've tried disabling v-sync, but it did not work.
What fixed it for me was disabling vsync in options.txt and setting my framerate (in options.txt) slightly higher than my monitor supports. (e.g. 60Hz monitor would be 61 - 70) That seems to have stopped the input delay.