Chrome massacres my 2012 MBA, the fan spins up within 30 seconds of launch. Firefox runs smooth as butter, mucho tabs and no fan. It seems people have widely different experiences, very weird. I wonder if it's a graphics card thing.
I'm on a Mac, a 2015 MacBook Air and a late-2012 Mac Mini, and don't have any perf problems with Firefox, using the standard, public builds (so not the dev ones). This is with an around 10-15 tabs open, with sync, and 10 add-ons of various stripes.
Then again, I don't do heavy web development or have a tab open with e-mail all day (e-mail is in Thunderbird) so maybe that makes a difference?
Pretty much the same here. FF has always been a battery eater, and even if only one tab is open, it's the sole app in the "Apps using significant energy".
I have a MacBook Pro. The fan spins up sometimes. So what? It also spins up when I’m doing other tasks. I’m always plugged in. So I have no opinion to share about battery performance.
Different commenter here, but same issue as the parent. I'm on a 2016 MBP. When I use Chrome, my fans stay off or at around 1200rpm at all times unless I open a video or a Twitch stream, at which point they jump up to around 1400rpm and the highest the CPU temp gets is around 50c.
On Firefox, my fans will randomly jump up to 3000rpm when doing only normal web browsing, even on simple sites like HN. I'm using FF right now to post this comment, and as soon as I opened HN, my CPU temp went from 40 to 50c. And this is the only tab I have open. If I open a video, or heaven forbid a Twitch stream or Google Maps, my fans instantly go to 7000rpm and my CPU temp goes to 70-80c. Even just opening Gmail makes FF go haywire. And it isn't just "my fans spin up, big deal". Browsing the internet on FF turns my MBP into a slag of near-molten metal that is too hot to even touch, and I can only imagine what it's doing to my battery life.
I want to like FF, I really do, but this is simply a dealbreaker for me, and even though it's a known issue, Mozilla seems uninterested in fixing it (I have previously seen a response from Mozilla that essentially amounted to "it's hard for us to optimize FF for certain sites, so we aren't going to even try").
It's clearly not an issue for everyone, but I definitely have noticed that I'm not the only one who has these issues, either.
Exactly the same with me: I tried switching to Firefox 63 last week on a 2015 MBP running MacOS 10.11, and compared to Chrome it seems to use a lot more CPU and thus makes my machine run noticeably hotter.
I guess this might be due to the new Rust layout engine I've heard about which is more parallelised?, but even just having a single tab playing youtube or a gif uses more CPU in Firefox, so maybe it's something with hardware acceleration?
It's funny how the promise of multicore CPUs was that appropriately engineered workloads could hit new heights of efficiency and overall performance but the cynical reality is that I'm glad for the most part that the partitioning between cores puts a hard limit on how much still commonplace single-threaded processes can take the piss.
> even just having a single tab playing youtube or a gif uses more CPU in Firefox, so maybe it's something with hardware acceleration?
My investigations (their bugzilla, the news about their company, I've been following for a long time) point to the opposite: it's the "old code" which nobody wants to improve: it doesn't help if the "new" code is fast to draw Some detail when the "old" decides to draw or update the stuff that doesn't even has to be updated or drawn. And it's not just drawing too, it's all the processing that happens during the life of the page with the "moving" images. Nobody, as "especially managers in Firefox." There was a number of developers in some Asian country, paid by Firefox, who were in charge for fixing in the old code, and they were simply fired. It seems it's not "strategic" for the managers to "fix" things, only to "experiment" with "new" things like ads or "new technologies" or whatever.
The "more CPU and GPU use" of Firefox is absolutely observable on any platform, not only on Macs. There are also the bugs submitted, but it doesn't seem that there's any priority in fixing them. From their perspective "it works, it's just that those who measure such use notice it." It's of course not so. The battery is empty earlier, the notebooks are hotter, the response lags. There are reported bugs demonstrating exactly what you observed: compared to any other browser even a single video on the "modern" site in Firefox needs much more processing power. It’s easy to reproduce in Windows too.
But obviously fixing the performance problems is not priority for the managers, when there's anything "new and shiny." Because they don’t see that as serious bugs: “the same page uses 10% of the max possible power in Chrome but 20% in Firefox.” “Who cares?” It’s too long-term goal.
