This isn't yet fully on par with Chrome's multi-process implementation, as Chrome also separates individual tabs' content processes (so, if you load many tabs i

This isn't yet fully on par with Chrome's multi-process implementation, as Chrome also separates individual tabs' content processes (so, if you load many tabs in a short time, those tabs will generally render better in parallel), and also, Chrome separates each individual extension into its own process, whereas Firefox only has one process for all extensions, but, if I remember correctly, current numbers are that this raises RAM usage by about 20%. The individual tabs in individual processes are also planned (and yesterday, I got a "The bad news first, this tab crashed"-message on Firefox Nightly, meaning that this was probably just pushed to Nightly), and the individual processes for individual extensions will most likely be implemented with their implementation of WebExtensions (Chrome's extension API) in the future. So, currently, it can't quite compete in theoretical performance when looking only at multi-process, but is also still miles off in terms of RAM usage. Personally, I don't think that they'll come close to the amount that Chrome uses, mainly because they've always been a bit more conservative, i.e. acknowledging that people occasionally use their computers for other things than browsing the internet, but yeah, we'll have to wait and see how it plays out in the end...