Nope, that doesn't work. I have it at one (default) and it's still spawning too many processes. I guess it's part of how things work now with FF. You get a snappier experience in exchange of higher memory usage because it's multitasking. If only we could turn that thing off.
> To disable e10s/multiprocess go to about:config by typing it in your URL bar. Search for browser.tabs.remote.autostart using the search box on about:config. There may be multiple results. Set them all to false and restart the browser (if there are no entries, create it as a boolean and set it to false).
The setting that Severine mentioned controls the number of content processes, which is the number of processes that Firefox uses for its tabs.
It will still have another process that controls all the UI and all those browser tab processes, a process for sandboxing extensions/plugins and then even more processes for miscellaneous things, for example I think asynchronous scrolling has another process and when doing performance improvements, they often just stuck long operations into a separate process.
