I agree with you,Moonchild dropped support so early for non-sse2 hardware due to the fact they won't let people run Pale Moon on museum-grade systems,while Mozilla would support it as long as possible,which by 2016-2017,they dropped support for non-SSE2 hardware,starting with 48.0.2 for Windows and 52.0/52esr for Linux,and dropped by 49.0 on Windows and 53.0 for Linux. For linux is different story,if you run on Debian or any Linux Distro based on Debian,like Ubuntu,you know you can use 128esr on non-SSE2 systems.
Thanks @roytam1,modern browsing on XP,Vista, and non-sse2 systems wouldn't be possible without you. And thanks Moonchild and your group of devs for making UXP and improving modern web compability while keeping support for XUL and NPAPI.......