This has come up on several sites lately and, as I had never heard of it, I did a quick Google check.
Looks like a good addition.
That’s addition, not replacement, but since I don’t use Adblock Plus -as NoScript blocks many ads anyway- it may be a good companion.
Posting from here cause it has more info and pretty pics. 😉

” Bluehell Firewall is a lightweight ad-blocker add-on developed by Diego Casorran for Mozilla Firefox. This the same developer who created an add-on to prevent facebook phishing on Firefox. This add-on weighs only 30 Kilo Bytes which makes it non compromising with browser performance but comes with price. Lightweight means no configurable settings. So, you can’t depend on this add-on for complete elimination of annoying ads, particularly those non Google ads and private ad pop-ups. “

Source: Browsers Addon
More  Bluehell Firewall, lightweight Ad-Blocker addon for Mozilla Firefox.
From the developer:
” …Next i’ll let you decide if this is for you… as long performance is in your mind, it should.

You can turn the extension on/off at any time by clicking the toolbar button (Fx Desktop), or touching the menu item entry (Fx for Android)
What’s next for Bluhell Firewall
ATM this is a option-less extension, but we’re considering adding options/features which are most demanded by our users.”