Session Saver is a very handy and productive extension that I recommend to everyone. I didn't understand how useful it was until I installed it. It is one of those simple things that you would think is easy and you would not expect there to be much but the person that makes this extension has done it right. It puts a little button on your navigation bar that allows you to save a session, so it is almost like another "favorites, or bookmark" that you can use at the touch of a button. When you have a session go down it will ask you if you would like it restored as you are booting up. There are many other things built into this little button. Install it and use it forever!
After you install this extension just reboot your browser and then right click on your navigation menu and select "customize" then pick the "Session Saver" button and drag it onto your navigation bar and you are done.https://addons.mozilla.org/extensions/moreinfo.php?id=436&application=firefox