If you are not aware of it already, Adblock Plus is one of the most resource intensive browser add-ons out there. Yet many of use it to stop annoying ads, flash etc. uBlock is a new bowser add-on that brings to you the functionality of Adblock Plus, only at the cost of lesser resources. There are other alternatives like Disconnect and Privacy Badger but none of them are as light as uBlock.
uBlock is not just an ad blocker, it is a generl purpose blocker which uses lists like EasyList to block websites. EasyList, Peter Lowe’s Adservers, EasyPrivacy are enabled in uBlock by default. It also supports hosts files. There is an advanced user mode which allows more fine-grained control on the extension like dynamic filtering, which works like a firewall with custom rules.
From the authors performance analysis results, uBlock uses lesser RAM than Adguard, AdBlock and Adblock Plus, much lesser processing and blocking count better than all (second only to Ghostery) these three.
The author advices not too use any other blocker along with uBlock as uBlock can handle things better than all of them.
uBlock is available for Google Chrome, Firefox and Safari. It also works great on Yandex Browser which I am using.