For many years I was using a relatively ancient quad-core AMD A8 APU with 8 GB system memory on a desktop running Win7/115esr and RX 570. I was mostly using it play older MMO games while having browser open for wiki and some personal web apps.
I recently got a new gaming laptop with a Ryzen 350 and 16 GB RAM and a RTX 5060. Quite the improvement was noticeable across all applications and games, as one would expect. Except, this new PC came with Win11. Imagine my surprise when I could no longer seamlessly play games and use the web simultaneously with a simple alt-tab. For some reason using the web slowed to a crawl whenever I had a game open - the same games as before when played on a much weaker PC.
So when I got around to doing a little examination I found Firefox using the efficiency mode in Win11. As the internet seems to explain, efficiency mode is intended to preserve battery life by throttling the CPU. And yet, this was happening while I was plugged in and the battery was fully charged. This seems to follow many similar design choices at Mozilla where devs seem to be so eager to be the good citizen that they neglect the needs of the user and worse, decide for themselves what those needs are without asking the user (the option to turn off efficiency mode is HIDDEN in about:config rather than being a user-facing setting). It clearly does not look at the actual context of whether the PC is even running on the battery before crippling the browser's performance. I have to wonder whether efficiency mode is also applied to desktops that don't even have a battery.
And before you respond by saying efficiency mode is managed by Windows, that is not good enough. Firstly, I don't trust Windows to do anything correctly and the only reason I have it is because of the games. But furthermore, Windows has only gotten worse since 7, and the OS was the last reason I would want to upgrade which is how I held onto the old PC for so long. I'm saying this because Mozilla might want to consider, and actively investigate, whether Edge suffers as badly as Firefox does when put into "efficiency" mode and whether Mozilla should be trusting Microsoft with a license to cripple their software's performance. If not, then Mozilla should be more proactive in making sure that such things can only happen when it is clearly of some benefit to their users, and otherwise make this config option more visible.
