that's just not true... i've used firefox consistently since v. 0.3 (phoenix) so that's at least one. plus a couple others in this thread make a few. i bet there are a few more out there too, so that makes a bunch. =)

anyways, i have ~350 tabs open on firefox 54, and so i can't wait until 55 lands to see this great improvement.

the chrome lead for mac told me that they too are working on better performance with 100's of tabs open and that should land sometime soon as well (even so, i'm a diehard firefox fan so it will be hard to make me switch).