Opera is the first major browser to bring native ad-blocking technology directly to its browser and here ad blocking happens at the web engine level.
Enable native ad block feature in opera
Update your opera browser to the latest version, that is opera 37 and later.
Click the opera main menu button and select Settings.
Under Block ads, tick the “Block ads and surf the web up to three times faster” checkbox.
You can also manage exception by clicking the Manage exceptions button below the Block ads and surf the web up to three times faster checkbox.
Click on the ad block icon on the browser bar for more information, including the number of blocked ads, a speed test, and a site-specific switch for unblocking ads.
You can also test the speed of the website with and without ad blocker by visiting below url in your opera browser.