I've used Arc probably 90% of the time for the past two months. One thing that I haven't seen mentioned anywhere (even in their literature): it's very lightweight on memory usage.

I've noticed recently that Safari uses 1/3 to 2/3 of a gigabyte for each youtube tab, or gmail, or <many other sites>.

Arc uses roughly 25% of that.

Also, Arc's efficiency as tabs build up seems to grow faster than Safari's although that's harder to quantify. But in concrete terms, Safari puts my M1 Air's memory into the yellow in activity monitor almost immediately. Arc regularly stays green with 20-30 tabs open.

There are other nice things to consider, but that's huge for me.