I need to shorten the time between two server requests. Each time it takes about 2 seconds. It is too long.
For example, I have an app that lets you add numericInput. You have to wait two seconds between each addition. I see that it is an imposed delay because when I press the add button several times, the server records my clicks and gives me the number of inputs corresponding to the click. Only this is done roughly after the two seconds.
We don't have enough information to directly address your issue.
You could investigate profiling shiny apps (use of profvis etc.) to understand timing issues; you might also think about making a reprex for your problem.