I assume the problem is just that it seems to be moving towards completion at a snail's pace. It certainly feels like I have been hearing about it for a LONG time without a stable release.
Yeah, but it's a massive reworking of the FF internals, so it took a long time to complete. But I'm using it now, and it works pretty well.
My only hitch was needing to turn off some older add-ons. While Mozilla is still doing a slow roll-out, it disables E10s if it can't ensure your plugins will work. (One of mine was a HN add-on, amusingly.)
The e10s project actually stated back in 2009. The project was put on hold in 2011 because the architectural changes and add-on compatibility breakage was deemed insurmountable. In 2013, the project resumed and has been chugging away since.
You can see 2011-2013 pause in the revision history of Mozilla's Electrolysis wiki page:
I made a burndown chart of the e10s bugs in Bugzilla that shows the development progress. The bug high water mark was in 2016 and today at least 2,495 bugs (specifically tagged as e10s related) have been fixed:
This is kinda confusing, but that button only exists in Nightly and Developer builds. Here's how to check, enable, and force-enable it for regular builds: https://wiki.mozilla.org/Electrolysis#Testing
I did have to force enable it as a few plugins didn't official support it yet. So far it's been amazingly stable though and had sped up my browser considerably.
> It's not process-per-tab like Chrome, it's just 2 or 3 processes.
Chrome is not process-per-tab - it's process per domain. (Even that's not true - sometimes tabs from multiple domains will still share the same process).
Firefox currently uses two processes (one for the UI, and one for rendering pages), but from a technical standpoint, that's the hard part, and that's what took so many years to develop. Once you have separated UI and rendering processes, going from 1 rendering process to multiple is relatively easy - you can already configure Nightly to do this, and Mozilla is basically just waiting for (a) e10s itself to rolled out more broadly, and (b) empirical evidence on what the right number of processes is, as (a) happens.
There are some downsides to doing true process-per-tab (the main one is that it's absurdly inefficient with memory), so ultimately Firefox will probably land on something in between (like Chrome and IE do).
