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?