Why do ads slow web pages down?
Each ad space makes the page do extra work. Its script has to download, then run an auction, contact other ad and tracking companies, fetch the winning ad and often load more scripts after that. All of it competes with the page you came for: for your connection, and for your browser’s attention.
- More waiting: every extra request adds download time and browser work, especially when it contacts a server the page has not used before.
- More processing: ad and tracking scripts keep running while you read, which can make ad-heavy pages stutter when you scroll.
- Jumping layouts: ads that arrive late push the text down just as you start reading.
What changes when AdFender blocks the ads?
The requests are never made, so none of that work happens. AdFender refuses the ads and trackers before your browser fetches them; a blocked script cannot call anything else, so everything it would have loaded disappears with it. With HTTPS filtering on, AdFender also hides the empty spaces the ads would have filled, so the page often closes up around them instead of jumping. On an ad-heavy page that means fewer requests, less data and less work, and the page often settles sooner.
How can you compare a page with and without AdFender?
Open a busy news or recipe site and let it load. Then right-click the AdFender icon in the system tray, choose Disable filtering and then 1 minute, reload the same page, and see whether you notice a difference: how long it takes to settle, how much moves around, how smoothly it scrolls. Try it more than once — the ads change from one load to the next, and a page you have just visited loads faster anyway. Filtering comes back on by itself when the minute is up.
Where is the difference small?
On sites with few or no ads. Banking, government and shop checkout pages load about the same either way. The gain is largest on news, recipe, forum and free video sites that rely heavily on advertising.
Does AdFender itself slow anything down?
AdFender is designed to stay light. Checking a request against the lists is quick, and AdFender remembers the decisions it has made recently, so a request it has just seen is answered almost at once. Reading inside secure pages adds a little work per page, the trade for being able to remove ads from inside them. On an ad-heavy page, not loading the ads can save more than that work costs, but the overall effect varies by page and by PC.
The same blocking saves data too: how much data does an ad blocker save?