I'm curious -- if this is basically a scheduler for tabs onto system processes (which it seems to be), what's the impact on input latency? I've read in multiple places that Chrome's input latency is worse than it could be because of multiprocess, so I'm really interested to see some input latency benchmarks.

Additionally, how are tabs sharing the same process isolated from one another? Chrome uses Linux namespaces for each of its processes, and this keeps tabs separated by a sandbox that requires a kernel exploit to break out of, how does Firefox's sandboxing work within a process?