I feel exactly the same when I read people saying that Firefox is faster than Chrome. It's been exactly the opposite for me and for everybody else I know on all kinds of computers and mobile phones.

https://www.phoronix.com/scan.php?page=article&item=firefox6...

https://www.phoronix.com/scan.php?page=article&item=firefox6...

Personally, I'm working towards moving to Vivaldi...

I have some sympathy for those complaints: I've been using Firefox since 2004, but for whatever reason I can't use it on my lab computer. It's a ThinkPad t430 running windows 10, and on that machine Firefox will slow the machine to an absolute crawl even with only 3 tabs open. I spent an hour trying to diagnose it to no avail (I can't just install Linux, I have some serial hardware that is windows-only) before just giving up and switching to chrome.

However, this is the only time I've encountered this issue, and I tend to think it's more likely an issue with the windows installation than Firefox. I'm just too lazy to reinstall, this isn't my main computer after all.

Exactly. This is what fixed this issue for me as well. What I haven't been able to fix is that new windows open rather slowly.

I'm so used to scrolling by keypress (i.e. any of the vim-like extensions), with smooth scrolling disabled and a higher scroll step, that I just recently noticed that this reduces resource usage/heat.

But then you don't have smooth scrolling.

Enabling apz kinetic scrolling is another approach. That cuts the lag by about 90%, getting it much closer to chrome.

It's smooth as butter on my early 2015 macbook air too. I suspect the issue is related to "retina" screens, which I don't have. (a 2009 mbp doesn't either iirc, right?)