NovaBlock vs AdGuard: faster on every page we tested

AdGuard is a large, well-established blocker with one of the biggest filter catalogues in the business. We benchmarked NovaBlock against it under identical conditions.

NovaBlock was faster on all five sites, and on the heaviest one by a wide margin: 1021 ms against 1752 ms on Tom's Hardware, a 731 ms difference. AdGuard was in fact the slowest of the four blockers we tested, and on two of the five sites it was slower than running no blocker at all.

Its defaults are unusually conservative. AdGuard's own setup screen ships with tracker blocking and social-widget blocking switched off, and offers them during onboarding. We enabled both, as a privacy-conscious person would. Anyone who clicks straight through that screen gets substantially less protection than the numbers above — which is worth knowing whichever blocker you use.

It ran into a browser limit, not a bug of its own. When we enabled AdGuard's annoyance filters, Chrome switched them back off. AdGuard's own Rule Limits page reported that Manifest V3's cap on active built-in rules had been exceeded and the browser had disabled its filters, keeping only the defaults. That is a genuine platform constraint that every Manifest V3 blocker lives under, and it is not AdGuard's fault. It does mean the strongest configuration AdGuard offers is not one Chrome will let it keep.

Bandwidth, and it's a real win: 24.0 MB against our 26.3, a 25% saving against our 18%. It also blocked slightly more requests, 127 to 108 — though it still contacted more third-party servers than we did, 32 against 28.

AdGuard asks for eleven browser permissions including the ability to run its own code in your pages, read your cookies, and observe your web requests. We ask for seven and none of those three.

* Why “requests blocked” can be misleading. This number measures blocking style as much as effectiveness. NovaBlock blocks tracking companies at the domain level — the script never loads, so the twenty requests it would have made never happen, and are never counted as blocked. Blockers that let the script run and then kill each beacon it fires score twenty for the same outcome. On Marca, Ghostery blocked 68 requests to NovaBlock's 9 while still contacting more third-party servers (16 against 13). That's why we also report third-party servers reached, which this effect doesn't distort. The gap isn't purely cosmetic — Ghostery genuinely transfers less data overall — but the raw count overstates it substantially.

† Why our tracker score may flatter us. We check whether the JavaScript object each tracker installs is present on the page after loading. Some blockers replace a tracker with a harmless local stand-in rather than blocking it outright; the stand-in defines the same object, so our test records it as “ran” even though no data left the browser. On this measure, their better technique scores worse. We report the figure because we measured it, and the caveat because it's true.