[floil]

Yes, but site per process is harder: iframes need to be booted out of process when they cross a site boundary.

To illustrate how much complexity this brings, consider a browser feature like find-in-page. It used to work by traversing the document and descending into subdocuments synchronously. It was basically a big for loop. With the page and its iframes split across multiple processes, now we need a protocol and interprocess communication to coordinate the find operation, and assemble the matches together into a tree. The results of this async operation can arrive in any order, and you need to filter out late arriving responses for previous queries, when the user modifies the search string.

This pattern needs to be implemented, rinse and repeat, for hundreds of subsystems. It was really hard.