Also the bazillion extension that exist for Firefox are not really helping.
A "task manager" to be able to keep on eye on all extensions memory consumption (and be able to kill the extension from the browser) should really be helpful.
Yeah, it's not really great either.
The about:memory page in Firefox is a little bit too technical compared with the about:memory in chrome that is, at least, simple and easy to understand what is going on.
In Firefox I still see a lot of memory commited to tabs that I've closed long ago, and can't really get a breakdown of my extensions memory usage.
Also what I was wishing is something more like a os task manager. Where I could kill or restart extensions that are using too much memory like I can do to normal applications.
Simply stating that this extensions is using too much memory so don't use it (a la IE) won't help. If that extension is the main reason I'm using your browser I'm not going to turn it off.
I'm not saying it would be easy or even doable right now, it's just what I wish to see in a future web browser to keep the memory down and prevent me from killing it and restarting it twice a day while working.
about:memory is intended to be a tool for developers and highly technical users. But we're getting close to the point where per-tab memory reporting will be feasible, see https://bugzilla.mozilla.org/show_bug.cgi?id=687724, which is currently blocked on some other infrastructure changes.
As for measuring memory consumption of extensions, you're about the 1000th person to suggest it :/ New-style ("JetPack") extensions have some tracking, but old-style ("XUL overlay") extensions are really hard to measure, unfortunately.
If a critical extension is using too much memory, one option that might be suitable is to create a separate profile. E.g. Firebug leaks a lot (https://bugzilla.mozilla.org/show_bug.cgi?id=669730) and some people only need to run it occasionally. Depends on how often you use the extension, of course.
I think the point of about:memory in Firefox is not to a task manager, but to allow the developers to know what is going on. If I report a high memory issue, I can copy/paste about:memory into the bug.
Now, on the other hand, I have been wanting a real task manager in browsers for years. It was one of the first things that got me excited about Chrome.
Also the bazillion extension that exist for Firefox are not really helping.
A "task manager" to be able to keep on eye on all extensions memory consumption (and be able to kill the extension from the browser) should really be helpful.