Google invested millions in making the fastest JS engine called V8. It is so good that it made JS a feasible backend language (node.js). I have a really fast machine so JS scripts cannot slow it down and Firefox's spidermonkey is more than fast enough and I really enjoy Firefox user experience
It is supposed to replace it's old reddit counterpart, here is an example of a good they knew post.
Any new content is welcome, lemmy definitely needs more content. So stop lurking!