Earlier quoted context omitted.
Firefox does seem to have really improved over the last few iterations, performance also when large numbers of tabs open. I cant find the link right now, but there was a nice timings done where Chrome was using less CPU at lower tab counts, but when it increased count, the CPU utilization was considerably higher than FF. I'll be giving it a fair shake for a few months.
I use Firefox out of principle and because of Sidebery, but WOW, Chromium is faster by a lot from my experience. That is fresh Chromium vs. configured and used Firefox, though.
At a first try Sidebery looks and feels more modern/slick! Might be what I was looking for!