This Firefox extension kills the pesky problem of noisy web pages hiding in your tabs
The Firefox add-on Open Link in Silent Tab gives you the option to open a tab without loading the corresponding webpage. Once you switch to that tab the page automatically loads. The downside to this is it will slow down your browsing a bit since you'll have to wait for the page to load. But it also makes it easier to have multiple tabs open without slowing down the whole program and also means you don't have a bunch of auto-playing videos going off at once.
To start, you'll have to download and install the add-on from Mozilla's add-on gallery. Once it's installed the add-on should start working right away.
To test it, right-click any link and you should see an option in the context menu that says "Open Link in Silent Tab." Pick that and a new tab opens almost immediately without loading the page. Click on the new tab and the page will load right away.
If you are a fan of shortcuts rather than right-clicking, there are options to use mouse-keyboard shortcuts instead such as ctrl + alt + left-click.
What it doesn't have is an option to make opening the page in silent mode the default behavior. If that's more appealing then try Load Tab on select by the same developer.