Do Ad Blockers Slow Down Your Browser

The Myth

Many people worry that ad blockers add overhead and slow down browsing. The reality is the opposite.

The Reality: Ad Blockers Make Browsing Faster

Why Pages Load Faster With an features" class="doc-internal-link">Ad Blocker

Without an ad blocker, a typical news site loads:

80-120 ad-related network requests
2-5 MB of ad scripts and creatives
10-20 tracking pixels
Multiple real-time bidding auctions (50-200ms each)

With an ad blocker, those requests never happen. The page loads with just its core content.

Where the time actually goes

We don't publish load-time figures for named sites, because the honest answer is that they depend on the page, your connection and the day — an ad-heavy news front page and a text-only article are not the same measurement, and a number that ignores that is worth very little.

What is predictable is the mechanism. A blocked request is never made, so its bytes are never transferred, its JavaScript never parses, and its iframe is never laid out or painted. On a page carrying dozens of ad and tracker requests that removes real work. On a page carrying none, it changes nothing.

If you want a figure for your own browsing rather than someone else's, the DNDShield popup counts what it blocked on the pages you actually visited.

Memory Usage

Each ad iframe uses 10-50MB of RAM. On a page with 10 ads, that's up to 500MB. Blocking ads keeps your browser's memory usage low.

Does the Ad Blocker Itself Use Resources?

Yes, but very little:

Modern Ad Blockers (Manifest V3)

Extensions like DNDShield use Chrome's native declarativeNetRequest API. The browser itself handles the rule matching — the extension just provides the rules. This uses near-zero CPU and minimal memory.

Older Ad Blockers (Manifest V2)

Older extensions like the original uBlock Origin intercept every request in JavaScript. This uses more CPU but is still far less overhead than loading the ads themselves.

When Ad Blockers Could Slow Things Down

Rare cases:

Extremely large custom filter lists (100K+ custom rules on top of defaults)
Multiple ad blockers running simultaneously (they conflict and double-process requests)
Very old hardware with limited CPU

Outside those cases, blocking removes work rather than adding it.

FAQ

How much faster will my browser be? It depends entirely on the page. Sites carrying a lot of ads and trackers have the most to remove, so the difference is easiest to notice there; a page with few or none has little to gain. The blocked-request counter in the popup is the honest per-page answer.

Will an ad blocker save battery on my laptop? It should help, for the same reason it helps speed: scripts that never run cost no CPU, and CPU is what drains the battery. We haven't measured this ourselves, so we're not going to put a percentage on it.