How do you get rid of Firefox's windows decorations in Linux? All I could find was for Windows, except one gnome-based extension which is known not to work reliably.

Also, checking for updates when I start my browser is the worst possible time UI-wise. I start my browser when the site I want to visit is at my fingertips, and my working memory is fading as I am waiting for my computer. How do you customize this away?

Sure, the bookmarks bar being always-visible or never-visible is a minor defect, but it is still worse than Chrome's show-in-new-tabs behavior. Showing menu bars and window decorations by default shows bad judgement, but indeed that wasn't the reason I couldn't stay with Firefox. It felt slower, had annoying wasteful window decorations, started with annoying extension version checks, and let bad web apps interfere with all my tabs.

Do you have actual responses for my actual points besides "you didn't really try"?

Maybe multi-process is the reason... I've recently started using Chrome more on my sub-notebook because Firefox gets really choppy even though it has lower memory usage. Perhaps the explanation is Chrome can be scheduled to all four of my 1GHz CPU cores, as compared to Firefox which will be on just one?

Nope. Threads can use multiple cores as well. No need to launch separate process for it.

Ah yes, of course. I should have remembered that. So Firefox is multi-threaded now?

As far as I know, it has always been. Unlike javascript which usually runs in a single thread, the browser itself is free to use as many background threads as it wants to load resources, render graphics etc. Only javascript is usually run as single thread per tab (unless the webpage uses web workers).