Part of the memory increase was caused by the new JIT. There has indeed been work done recently to bring memory back down. You can see a list of fixed and sti

Part of the memory increase was caused by the new JIT. There has indeed been work done recently to bring memory back down. You can see a list of fixed and still-open bugs here: https://bugzilla.mozilla.org/showdependencytree.cgi?id=598466 https://bugzilla.mozilla.org/showdependencytree.cgi?id=59846... For example, this bug significantly reduced memory usage, and was fixed less than a month ago: https://bugzilla.mozilla.org/show_bug.cgi?id=631951 https://bugzilla.mozilla.org/show_bug.cgi?id=631951 However, there are many memory vs. speed trade-offs in software, and as memory continues to get cheaper, you'll likely see all browsers choosing to use more memory in order to run faster.