it’s not mainly how many but how long. I leave my desktop running for weeks, and there was a while when clearing Firefox’s cache was the main reason I needed to restart. I do leave something like ~100 open at a time.
htop/top are a bit tricky because Firefox spawns a bunch of sub processes, so it’s frequently an undercount; I forget whether htop accounts for that.
I do leave something like ~100 open at a time
That’s… that’s too many tabs.
Think of it as transitory bookmarks. It’s something like 20 tabs across 5 different windows for completely different contexts: dev pages in one desktop, work google docs in another, personal email/music/etc in another, gaming in a fourth, social media in a fifth, etc. It means I can easily context switch when I need to without having to dredge the exact things I need out of my own memory.
I had the same problem - this extension saved my RAM: https://addons.mozilla.org/en-GB/firefox/addon/auto-tab-discard/