Firefox has more than two process classes. I'm probably missing some still, but it separates at least into main process, content processes (tabs), NPAPI plugin

Firefox has more than two process classes. I'm probably missing some still, but it separates at least into main process, content processes (tabs), NPAPI plugin process and extension processes (at the time of his writing, I believe this was one big extension process still). There's also a process for Asynchronous Panning and Zooming (APZ), but that probably doesn't help much with security.