Your comment reminded me of the essay hence posting it here.
Gmail app is still pretty fast. When they launched the new one, I was hoping to find a function where you can run a fast version (just like html for slow connections in old gmail, which was super quick even for slow connections) but could not find it anywhere. You can switch back to old gmail, that is faster (less slow) if you like, or if you like the smart compose, you can just kill the apps GMail loads by default - Calendar, Hangouts, keep, Tasks, and much more. Then it may become faster.