[ta1771]

Firefox runs multiple sites in a single process, its sandboxing doesn't come close.

[cmeacham98]

This hasn't been true for years (https://wiki.mozilla.org/Electrolysis)

[sciurus]

Actually, it is still true. Electroloysis split up Firefox into multiple processes, but not every site gets its own process. Work is underway to change this and achieve full site isolation in https://wiki.mozilla.org/Project_Fission.

(Disclosure: I work for Mozilla, but not on this)

[Drdrdrq]

Afaik, it uses Chromium's sandboxing?

That said, safety is about much more than just sandboxing.