How to determine if there is really any delay in text input with company completion?

Question

I use Company mode as completion. I like the gratification of instant completion popups. So I set the following setting:

(setq company-idle-delay 0.0)

So basically no delay before the pop-up appears.

However, I noticed someone said it would slow down the text input. When Googling around, I found no way to determine how this will delay the input of text. Any suggestion in order to determine the setting above will really delay the text input?

Answer 1

It will slow down your typing as much as the backends you use are "slow" (use expensive processing inside Emacs, or even do that mostly outside Emacs but produce completions synchronously).

To test, try mashing your keyboard under different values of company-idle-delay, and see if there is a noticeable difference in how quickly the characters get inserted.