You should probably check that.

A fresh hackernews tab of this thread uses 150MiB (Sandboxed) in Chrome for me, and HN is a pretty lean site by all accounts.

In Firefox (Linux) it says 34MB.

Weird, I promise I am not lying.

https://sh.drk.sc/~dijit/hn_tab_mem_usage.png

Do you use browser extensions? Perhaps they are adding to the memory usage (?)

Only bitwarden (no ad-blockers or anything).

https://sh.drk.sc/~dijit/hn_tab_extensions.png

EDIT: Looking into it, seems the tab memory viewer is only looking at the page and does not take extensions into account; if the extensions inject JS/Style to the page then it counts, and Bitwarden seems to only add a small amount of JS to find password dialogues. It uses memory, but outside of the tab viewer.