As I understand the situation: Mir borrowed code from wayland and this comparision does not make too much sense in light of that.

Most likely some patches to wayland would be enough to get what they wanted - instead now we have more fragmentation.

But the same comparison could be made about Chrome and Chromium, no?

But chromium and chrome do not lead to duplication of efforts: Chrome is basicly Chromium + addons - and chrome devs contribute to chromium - they supplement eachother.

Chromium/Chrome are based on Webkit (forked into Blink since Chrome 27), which in turn is based on KHTML/KJS. Chrome was built in large part by former Mozilla engineers, and Mozilla Firefox itself was built based on the browser engine open-sourced by Netscape as its swan-song gift to the open web.

No. Google supports Chromium, and Chrome has proprietary additions.

I do wish Chrome didn't exist, but I'm not convinced that this comparison works.

> I get that Chrome added a JIT javascript compiler, but hasn't Firefox since added that in response?

In addition to what @ergo14 said, Firefox had a JIT compiler called SpiderMonkey before Chrome was even released [1]. With that said, I'm sure there's cross-pollination both ways between OdinMonkey (Firefox's current JIT compiler) and Chrome's JIT compiler in V8.

[1]: http://ejohn.org/blog/tracemonkey/

Chrome performs a lot better, even now, which was its stated goal and what it was advertised as being about. The Ubuntu team has consistently failed to articulate what Mir is supposed to give us over Wayland.