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Comment by bryanlarsen | Hacker News Reader

AFAICT, his only attack against FF4 being a modern browser is that FF4 doesn't do process isolation on tabs, which I would argue is unnecessary.

FF4 has process isolation for plugins, which is super important. Process isolation for tabs protects against runaway Javascript, but you don't need process isolation to do that since the javascript engine is part of Firefox.

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Process isolation is a great feature but it has nothing do with page rendering. As a web developer, I'm concerned about how people will view and interact with my sites. If their browser does that correctly and quickly, that's what matters here.

If your browser has process isolation, a crazy bookmark system, skins, or an extension system those are just features for the end user and don't affect web applications running under it.

This is not necessarily 100% true. Process isolation affects your user's experience in an indirect way. As web apps become heavier and heavier they adversely affect each other more and more. Many times your sites perceived lack of performance is due to another misbehaving tab. Its true that standards support improves the singular experience of your site, but process isolation improves the combined experience of the web as a whole and allows everyone to do more impressive things.

A browser doesn't need process isolation to clamp down on misbehaving sites. It might be easier than doing it in the scheduler in your javascript & rendering engines, but process isolation is not necessary.

Process isolation on tabs, when combined with a solid sandbox, also prevents a browser exploit in one tab from compromising others.

It does not prevent it, it makes it more difficult. There is still communication between processes which could be exploitable. That being said, it certainly helps.

In theory, the sandbox should prevent it. In practice, of course, this is not the case.

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