Browsers and JS VMs are so widely deployed now that anything that can be done to make them faster or use less memory has a tremendous effect in the aggregate. W

Browsers and JS VMs are so widely deployed now that anything that can be done to make them faster or use less memory has a tremendous effect in the aggregate. What's really cool is that you can update a browser and suddenly the web starts working better for everyone who uses the browser. Browser memory usage does tend to creep up unless there is active work to keep it under control. So I think it is important to try and trim the fat where possible. Just look at Are we slim yet? to see Firefox's memory usage slowly growing over time. https://areweslimyet.com/ https://areweslimyet.com/ By the way, JS engine optimisation does seem like it is getting more and more complicated. I suppose most of the easy optimisations have already been done. Look at Safari adding a fourth layer to its JIT! https://www.webkit.org/blog/3362/introducing-the-webkit-ftl-jit/ https://www.webkit.org/blog/3362/introducing-the-webkit-ftl-... It's kind of crazy, but totally worth it! (IMO) The string slimming work in IonMonkey sounds like it got some memory improvements without too much more complexity. Remember the string logic is already complicated—around 6 different string types. The kinds of pages where I think you'd see a real memory improvements would be in JS-heavy pages which store lots of data in memory. These types of pages are becoming more and more common. I imagine it would also be a big improvement for any software running on Firefox OS. It would be especially noticeable because Firefox OS is targeted at low cost mobile devices.