It is available as an option. "dom.ipc.processCount" in about:config allows you to set the maximum number of processes that it'll use. Set it to something like

It is available as an option. "dom.ipc.processCount" in about:config allows you to set the maximum number of processes that it'll use. Set it to something like 1000 and it'll use a separate process for each tab (unless you actually open up 1001 tabs). They are also working on a UI for changing that max process count (don't think that's in Firefox 54, but I could be wrong), but that UI currently only offers values 1 through 7, as it's just really unlikely that a normal user would actually want to sacrifice their RAM like that.