Hearing your own voice delayed by some amount, 100 milliseconds IIRC, makes it very difficult to speak. There is the famous video by Microsoft Research on the effects of latency (delay) when using a pen. Dan Luu has done a series of articles on measuring latency because he notices the discomfort induced by the poor performance of modern peripherals and software.
A 60Hz monitor refreshes the screen every 16.67 ms If your OS or editor implements a double-buffering scheme, your keystrokes will on average be another half-frame behind that, so a display latency of around 25 ms.
At 240 Hz the frame time is just over 4 ms so the display will lag by only around 6 ms. You are a fiftieth of a second better off, minimum.
1. Delayed auditory Feedback https://en.wikipedia.org/wiki/Delayed_Auditory_Feedback
2. random article with link to youtube video: https://www.phonearena.com/news/Microsoft-has-created-the-fi...