Firefox is frustratingly slow for me. I can't use it, have to stick to Chrome. Chrome which, by the way, crashes after 5 minutes of using video Hangouts and brings my 16 gigabytes ram PC to a halt when I open too many youtube tabs.
But firefox scrolling is especially slow. irccloud.com is the main culprit (and I use irccloud a lot). It's pretty bad in gmail as well.
The react app my team is working on is also far slower in Firefox. Try scrolling this in Firefox and Chrome and see the difference (the scrubber is at the bottom of the blue area, like a video). Butter smooth in Chrome, horribly slow in Firefox: https://hsreplay.net/replay/7VAKLeMNaXvshAawnUUoni
This is super surprising to me, because irccloud is exactly what we use at Mozilla. Everyone seems happy with it's performance, and obviously most people are using FF.
If it helps, I'm running irccloud's "Ash" theme, with the sidebar on the left, monospace font, "nicknames on a separate line", "user icons" and colored nicknames all enabled.
It's pretty bad on both Windows 10 and Arch Linux (different computers). Worse on Windows, actually, but only after some time -- I'm in ~30 channels, fwiw.
As always it's probably a plugin. You could integrate the functionality of plugins which everybody uses, such as an adblocker (Instead of pocket? You are already doing it with the developer tools) -- but you get all your money from Google...
Tracking Protection is pretty much an ad-blocker. It's default-enabled in Private Browsing and you can enable in normal browsing, too, by setting "privacy.trackingprotection.enabled" in about:config to true.
Dragging the scrubber around updates at the same speed, really? I'm not on Nightly, maybe that's the difference, but if that's the case that's great news.
But firefox scrolling is especially slow. irccloud.com is the main culprit (and I use irccloud a lot). It's pretty bad in gmail as well.
The react app my team is working on is also far slower in Firefox. Try scrolling this in Firefox and Chrome and see the difference (the scrubber is at the bottom of the blue area, like a video). Butter smooth in Chrome, horribly slow in Firefox: https://hsreplay.net/replay/7VAKLeMNaXvshAawnUUoni