Bluehell Firewall is an extremely lightweight ad-blocking and tracking/ privacy protector.
How lightweight? As we write, the current version is a mere 42KB download, a fraction of some of the competition.
One reason for this is that Bluehell Firewall uses only five blocking rules. Apart from simplifying the add-on, it also greatly improves performance, as there are very few checks to make before any web resource can be displayed. Yet it still reportedly blocks about 7,000 .com and .net domains.
Another reason is that Bluehell Firewall's developer has concentrated on the core ad-blocking functionality, and not added any other frills, at all. There are no options or settings, you don't have to set up any subscriptions, it just works. (You don't even have to restart Firefox after Bluehell Firewall's installation.)
Arguably this does go a little too far. The ability to create a whitelist of trusted sites would be welcome, but, well - forget it, at least for now.
Bluehell Firewall scores well for ad-blocking, though, and it's definitely easy to use, so on balance it gets a thumbs up from us.