I have quit caffeine during 3 different decades - in the 80s, and then in the 90s and about 2 months ago. For me quitting black tea (coffee a few years ago because is upset me stomach) has made me less intense and less irritated. Most of all I have twice or maybe three times as much energy without caffeine as I had with it.

Here is my piece on it - "The Scourge of Caffeine":

https://medium.com/know-thyself-heal-thyself/the-scourge-of-caffeine-1ca0da6b7702?sk=4bddb29f5826ad6c5bfff4eab2fc2e45