You can check if e10s is available by going to Options -> General -> "Enable multi-process Firefox". I think what TFA means is that it's off by default (unless you don't use addons) until Firefox 49, but can somebody confirm that?
I definitely do
I can see a few things in about:config and about:support relating to it; it may be possible to get it going by mucking around with options but it's certainly not at the point to justify the headline.
I had this issue when I updated to 48beta a few weeks ago _specifically_ for multi-process. You can force enable it. Follow this: https://wiki.mozilla.org/Elect...