I've had my whole system lock up for minutes with 10 tabs open on Firefox as recently as last week. I still use it as my primary, but that does happen on occasion.
On chrome I've had 60+ tabs open for weeks without my system taking a dive.
This is on an ubuntu 19.10 system with 32gb of ram.
This seems extremely weird, never seen anything like that (I tend to have >100 tabs open). But of course "it doesn't happen for others" doesn't help you if somehow on your machine it does.
It's definitely strange. And I do at times have 50+ tabs open on Firefox, so I'm not saying it's a constant issue, but I do see it overload my system from time to time. When it does, I close a few tabs, restart firefox, and go on my merry way.
On chrome I've had 60+ tabs open for weeks without my system taking a dive.
This is on an ubuntu 19.10 system with 32gb of ram.