I’m all for people using Firefox instead of Chrome, but RAM being used up shouldn’t be a complaint unless something else needs that RAM. If it’s there, it should be considered usable.
I'm referring to the philosophy behind the usage of said allocated ram.
If you allocate 5 cookie jars to store 1 cookie in each jar, then that's not good.
If you store 2 cookies per jar, that's better already, but still kind of crap.
If the websites keep putting rocks in those jars, then you'll obviously run rampant with usage. (Read: https://tonsky.me/blog/js-bloat/ )
The goal is to store as many cookies in least amount of jars. You might crumble them down and reconstruct them later (compression and/or clever code) but that could take more brain (processing) power (of which we kinda have, especially on the desktop).
As you've said, it's often a tradeoff between processing power and memory usage and depending on the application, you can configure things the way you need them (at least when you're coding it).