Honestly, it depends on the game. Hence I suggest checking ProtonDB[0] for the games you are planning to play. Most of the reports also have details about CPU, GPU, GPU driver etc.

Anecdotally, I remember playing Team Fortress 2's native port on Intel i7-2630qm CPU on my laptop back in 2012-2013 at 1366*768 resolution with no major performance difference. (setting up bumblebee was not an easy task for me back then.)

[0] https://www.protondb.com/