A 10-15% speed bump in CPU performance is certainly nice but in most cases it's not going to be something that users are consciously aware of. Web page performance varies a lot due to network performance, new versions of websites being deployed, different ads being served, and so on. This noise obscures things enough that it probably won't be easy to attribute a change in performance to the browser if you're not looking for it.
But even if the users aren't aware of what changed, it will likely affect user behavior.
For the better? Hard to say. Websites that load a little faster are a little more addictive.
If they want to actually improve user experience they can always include uBlock Origin by default - its permissive license should allow this just fine.
Despite it being an absolute dumpster fire in other ways, the new firefox android almost has that. It's nice for telling my friends who I've gotten to switch over to just open firefox, open the hamburger and tap addons then addons manager, then tap ublock origin at the top of the list and that's all it takes to get my friends rolling with it. They're all extremely happy with the new firefox and don't notice how webpages are pretty broken in it now.
They could just show users the recommended plugins to install as part of user onboarding .
It is not just about privacy or blocking ads. It is matter of security . I am trust nytimes , I cannot trust every third party whose code nytimes decided to include. Who in turn has included a bunch that nytimes doesn't even know about. How can I trust a website when they themselves do not know what crapware runs?
There is a move toward 1st party proxys as a result of GDPR and similar ruling. Google has already published a framwork or something in that direction. It is not mandatory yet, but when the web moves in that direction there will be no blocking of domains any more. (Technical) Users won't even know that Analytics tracks them.
I'm dealing with a Firefox issue where painting on canvas with a CSS filter is magnitudes slower than Chrome. It makes my app almost unusable for Firefox users. Improving the performance would certainly make users notice since it's one of the most common complaints.
Stuff like CSS filters is generally going to be down to lack of GPU acceleration or video driver shenanigans, though some obscure filters still run on the CPU. If you run a filter on the entire page for example (some addons do this) it pessimizes rendering in a bad, noticeable way.
> Safari and Chrome both do blur on the GPU Firefox does it in software unless WebRender is turned on. You could try turning on the gfx.webrender.all pref and that should improve things.
In the Firefox Release channel, WebRender is currently only enabled on Windows 10. Windows 7/8 support should be coming soon in Firefox 83 (2020-11-17) and macOS and Linux after that. As you say, GPU drivers are the biggest problem.
I have an Intel video card (UHD 630), and Webrender (which I had to forcibly enable) is working very well. Video acceleration, too. Even with a 4K screen.
Firefox used to be a lot faster, and smoother, at rendering <canvas> than Chrome when I was developing early versions of my canvas library (around the mid 2010s). But then Chrome caught up and for the past couple of years has been considerably faster[1].
One thing that really annoys me about Firefox on MacOS is that they disable keyboard focus of links by default. Which is not good for accessibility - it took me days to work out why my accessibility testing demos were failing[2].
But even if the users aren't aware of what changed, it will likely affect user behavior.
For the better? Hard to say. Websites that load a little faster are a little more addictive.