With this addon, when you do "reload all tabs" then Firefox reloads tabs progressively. In other words, if you set "3" to the maximum number of reloading tabs and there is 4 tabs, "reload all tabs" command doesn't reload the 4th tab and reload it after the first tab is completely loaded.
This will useful for people using narrow band network.
Similar or Related Extensions
For restarting of Firefox?
BarTap stops loading of background tabs when you restart Firefox.