[CentOS] browsers slowing Centos 7 installation to a crawl

> In any case, Centos 7 has not always been this slow.
> Presumably something has changed.

Firefox especially, and to some extent Chrome, have both started using
much more memory recently (as in the last six months or so).  I run 50+
desktops on CentOS and I've noticed more and more of them getting low
on memory more often and almost always Firefox is the culprit. These
are systems with 8Gb that are struggling.

P.