Firefox is really ok.
Vivaldi doesn't make a huge difference in term of resources (albeit it does snooze unused tabs so you can spare some ram) but it gives you much more functionality for what it costs you in terms off resource usage.
But even if the browsers can do something about it, the problem really resides in today's web apps / web sites conception : When you say "Chrome uses too much resource", even if I don't use Chrome, I'm pretty sure this is a false statement if you are browsing, e.g, HN. Even if you open dozens of tabs of it.
No browser can do anything to spare your RAM if you are forced to open tabs on Slack, Gmail, JIRA or the generally poorly developed business software.
