Here's a classic from NNG on 'UX time scales': https://www.nngroup.com/articles/powers-of-10-time-scales-in-ux/ https://www.nngroup.com/articles/powers-of-10-ti

Here's a classic from NNG on 'UX time scales': https://www.nngroup.com/articles/powers-of-10-time-scales-in-ux/ https://www.nngroup.com/articles/powers-of-10-time-scales-in... You can infer from there that anything around/under 100ms will feel like direct manipulatio, interpreted by the person in the post as 'no request was sent to the server'. The same interpretation might not result from a non-technical person, it will just feel 'different' or they won't notice what happened and submit it multiple times, if there is no success message. You can also trace it back to one of their 10 heuristics: visibility of system status. If users cannot perceive a change because it happened too fast, the UI has failed and users don't know what happened. One of the reasons some websites add artificial delays, as mentioned in other comments, is not only to signify 'work' being done, but that flashing a spinner for a split second is also a bad experience. You're better off normalizing every action to take at-least-one-second, and ensuring the state of the system is always clear.