[Excavator]

I currently have 1290tabs in the tab bar, about ~40 of them loaded with memory usage around 2GB for the whole browser without noticing any issues.

My most CPU intensive extensions are Stylish @ 3%, µUblock @ 2%, and All Tabs Helper @ 1%. For tabs it's about:performance @ 22%, a YouTube video @ 6%, and a paused YouTube video @ 2%.

This is with Nightly (binary downloaded from Mozilla) on a 4core 3.7GHz AMD CPU, with an integrated 8core GPU: the A10-7850K running Gentoo Linux.