[dblohm7]

"Sadly Firefox 39 (nightly) still has no real multi process support. There are only two processes, the main process holds all tabs, the single child process 'plugin-container' holds all plugins (Flash, Acrobat, etc.)."

That is incorrect. There is one plugin-container for each plugin module. All Flash instances share a single plugin-container, all Acrobat instances share a single plugin-container, and so forth.

As for the e10s content process, for the moment there is only one content process. The plan is to get e10s working well with the one content process, and then start scaling that up to multiple content processes. Nightly is a bleeding edge development channel, after all.