I encourage anyone who wants to see the benefit of having a tmpfs in RAM to try relocating the firefox profile to a tmpfs (see https://wiki.archlinux.org/index.php/Firefox_Ramdisk). I've recently done this on my new system which normally has plenty of RAM to spare. The difference is quite impressive, even though I have a latest generation SSD. Mind you I've been bitten by this once. I kept too many tabs open while doing some simulation work on the side. When I tried to open one more tab, the whole system went into a complete freeze because it ran out of RAM (and I don't have a swap partition), obviously this happened when I was just booking a flight online, with only one last ticket available at this price.