Since my RPi4 is my workstation for a couple of weeks now, I find myself treating this little machine more gently, as in I close programs more often when I don't need them. I noticed I do this also with Thunderbird and not constantly having my email program open is a breeze of fresh air. You should try it.
NB What's also a breeze of fresh air (or rather, a lack of a thunderstorm) is the thing doesn't have a fan.