This plugin is free and is powered by Avast and is not a virus. By doing so, they can provide the user with relevant offers.
However, other than interrupting the browsing experience, it also offers many good deals, coupons and best prices by recording your information. This tends to interrupt the browsing experience and you may find it hard to remove from your computer. If you are an Avast user, then you might have encountered interruptions from a browser extension of Avast called the Avast SafePrice.