Yes, could potentially be related to a different CPU architecture, but could also be something else eg RAM capacity (I have 64GB) or Proton Mail settings (do you have offline enabled? I don't).
I have 64gb of RAM as well. I don't think I have offline enabled. My CPU is an i9.
I'm happy enough with my Mutt solution, and the iOS app is generally ok, and I do like the service overall, so while I complain it's not out of hatred. I just want the service to get better.
