Thank you for mentioning this. I've been getting frustrated with my Firefox install for a while because everything is so slow and it eats so much memory. After deleting the 200 service workers [1] I didn't even realize were installed, it is taking wildly less memory and seems generally snappier. I wouldn't call it "night and day", but it's faster.

I had been under the impression that service workers required approval from the user to be installed. I had service workers from websites that I haven't visited in years and don't even exist anymore, sitting there chewing on my RAM every time I started Firefox.

Also Twitter has also been broken for me this way for months.

Service workers have some nice features, but I submit that they need to be something to be whitelisted by users, not something websites can just toss in there whenever they feel like it. The odds of one of them screwing up and eating far more resources than they have any right to approach 1 as the number of them increases. I don't know exactly how they managed to collectively eat 2GB of RAM and I don't care; there is no way they were bringing that much value to me, especially as I permit no website to simply push me notifications.

[1]: A suspiciously round number; it was exactly 200. Is that a limit? I don't see it in about:config.