Firefox vs Chrome Performance: A language difference?

Like many folks, I've been pretty blown away by the speed of Chrome (especially with respect to running JavaScript intensive sites). Currently, I use both Firefox and Chrome (depending on what I'm doing), but primarily Firefox as there are still some addons I can't live without.

Though I am excited to see the Out Of Process (OOP) Electrolysis project (which is now in beta) and the upcoming JägerMonkey JavaScript engine, I've begun to wonder if some of the performance differences we're seeing are more deeply rooted. Now I do know there are things that are supposedly not possible with Chrome's extension support, and of course with greater functionality comes reduced performance. But I've lately been wondering if the differences are at the language level. Does the language each was written in greatly alter performance? Have a look at this graphic

Source: Ohloh

Just look at all that JavaScript! While some sources favor JavaScript as a "first-class language" (and maybe I'm misinterpreting their meaning here), I'm not convinced that makes sense for desktop applications. There are some advantages to having portions of Firefox be in a web language, it makes it easy for web developers to extend & theme. But I'm not sure it makes sense to use it as extensively as they appear to have done.

For example, it would seem that the addon manager (nsExtensionManager.js) and session storage (sessionStore.js) are both JavaScript. How do I know these are their names? I didn't look at the code, but apparently I was putting Firefox under a bit too much pressure and I got the message saying these scripts had stopped responding (not at the same time). (Though this does happen less often with my portable Firefox, so maybe I need to clear out the profile).

It will of course help when we have the content and the UI in separate processes, and maybe help some more when Firefox gets a faster JavaScript engine, but I wonder if you can ever get really good performance from a language like JavaScript. I'm not saying to write the thing in assembly, I'm just saying maybe it makes sense to write the lower level components in a lower level language. What do you think?

As two somewhat unrelated sidenotes: What do you think the impact on Firefox's future will be with the loss of their tech lead? And do you think Google will finance Mozilla now that they're in some competition with each other?