wrote

|I am sure most any user of Firefox has noticed in the last few months that
it has gotten to be a real
| memory hog.
|

People talk about this a lot. I haven't yet tried the newer
FF versions, but there are things you can adjust, while checking
memory:about won't tell you much that's actually useful. In
addition there's the obvious solution of paying attention. If
you have 10+ tabs/windows open you have no reason to
be surprised they're hogging RAM.

* Cache size. The majority of webpages therse days are of
no value cached because most are generated dynamically.
That means your browser will rarely be told that its cached
version is as new as the current version because the current
version is always brand new, even if it hasn't changed in 2
years.
But if you allow a big cache then FF needs to manage it
and search it with every page you visit. I allow 10-20 MB cache.

* Super cookies. FF calls it "offline user data". If you
frequent a site that needs up to 100 MB space on your disk
then you need this. I remember Vanguard LH once said he needs
it for an online game he uses. I've never enabled any offline
storage and never needed it. But if it's enabled, sites may use
it whether they need it or not. And why not? It allows them
to use your resources to spy on you. (Look for "dom.storage"
and "offline-apps" prefs.)

* Prefetch - Disable all prefetch options. Prefetch means that
FF will load links on pages you visit in the background, so it
can appear to be very fast if you decide to click on one of
those links. (I'm not kidding. It really does that! There's also DNS
prefetch, typically used to look up advertiser IPs as a webpage
loads.) Prefetch is a ridiculous waste and also a privacy intrusion.
It's allowing all sorts of sites to monitor you and run script
while you actually don't even know those sites exist. DNS
prefetch and webpage prefetch can also be prompted by the
webpage itself, if you allow it.

* Number of connections - I don't actually know whether
this will save on RAM, but it could be tested by setting a
low limit on the number of concurrent connections. Like
prefetch, there are several pref settings involved.

* accessibility.blockautorefresh - This will stop pages from
updating periodically without asking.

* sessionstore - Do you want FF to load all of your open pages
if it crashes? Then you'll want this. If you're not worried
about that you can save RAM by disabling Session Restore.

These settings get into a lot of nitty gritty detail. You
may not want to go to so much trouble. But you should
know this is only going to get worse as the Internet
becomes more commercialized and ever more websites
try to control what you see and do.