I am a serial tab abuser. Its my lazy Instapaper. As bad as that sounds on its own, I often would not close firefox, in fear of restarting it later and fire a cascade of page loads. After a few days FF would have grabbed a major chunk of my RAM (even with flashblock).

The Restore Control add-on https://addons.mozilla.org/en-US/firefox/addon/177558/ is a big relief. It opens a tab but does not load the content unless I actually click on it. I can now easily close and restore FF. It comes up in a (slowish :-) snap, as it only loads the last page that was active. The rest are opened as "empty" tabs to be loaded on demand.