It was true for me, specifically for my workflow, the websites I use and how I leave some specific tabs in the background.

I’ve used Chrome for many years before Firefox and it was always prioritizing JS responsiveness even when the app was in the background and not needed, so it consumed CPU cycles and battery power needlessly. I see now that Chrome enables a Low Power mode by default on battery and it’s unusable as scrolling gets janky. I don’t know if the overall experience has gotten better in the last year on Chrome.

Not sure what’s different about memory though, but Chrome always appeared like a memory hog when I tested both browser side by side on the same set of websites and same few extensions. Could be that it just caches more and that’s benefitting responsiveness

True for me too, much more memory efficient, especially with content heavy websites.