This is a nice, simple, and incredibly helpful add-on that seems to improve performance just by letting me open lots of stuff in the background and have it load only once I'm ready to view it.
It does have one issue that I've noticed, though. If I close a tab, then undo the close, the result is a tab with the raw "moz-extension" link instead of getting back the original page. I have to manually edit the link to remove "moz-extension://d22fa2fb-aba0-8149-97b5-e26191987d2a/html/tab.html?managedUrl=" from the beginning in order to get the original contents back. If that gets fixed, this will be the perfect add-on.