Chrome extensions can significantly slow down browsing – gHacks Tech News

Extensions are one of the strongest points of web browsers. They allow users to extend functionality, but this comes at a cost. A test of the 5,000 most popular Chrome extensions found that extensions can significantly slow down the browsing experience, with one notable exception.

The Debugbear team analyzed the performance impact of Chrome extensions in several ways, including the impact on CPU processing and website load time.

These are the main findings:

  • Even on standard websites, some Chrome extensions added 500 ms or more to processing time.
  • 86% of tested extensions have minimal impact on simple websites.
  • 1.7% of extensions add 500 ms or more to simple website processing.
  • On complex websites the processing time was 2000 ms.
  • The impact can be cumulative, meaning multiple extensions can have a greater impact on the experience.
  • Popular extensions with high processing times: Honey Automatic Coupons, Klarna Pay Later, Monica – Your AI Copilot, Capital One Shopping, Popup Blocker, Dark Theme, Malwarebytes, Dark Reader, DDG Privacy Essentials.
  • One type of extension reduces website processing: content blockers.
  • Extensions can affect any browser, including other Chromium-based browsers and Firefox-based browsers.

Impact on website loading time

Google Chrome extensions

Browser extensions can slow down website load time, especially if they are designed to run as soon as the page loads rather than when the page content is displayed to the user.

  • Extensions can add up to 1000 ms to the loading of simple websites.
  • Chrome extensions can also slow down interactions after a website loads, but these are less common and the impact is less than 50ms for all but a select few.

This delay is noticeable to the user because it takes longer for website content to be displayed by the browser.

Most content blockers improve the user experience

Content blockers significantly improve the CPU processing of websites and the page download site, especially on websites with many advertisements.

  • Some content blockers have reduced the processing time from more than 50 seconds to a few seconds.
  • Most have reduced the page size from 40+ MB to less than 5 MB.
  • Most reduce memory usage.
  • Notable extensions that performed well were: uBlock Origin, ScriptSafe, Privacy Badger, Malwarebytes.
  • The popular AdBlock Plus and AdBlock extensions performed worse and not much better than the browser without extensions.

The reason for AdBlock Plus’s poor performance is its acceptable advertising program, which allows some ads to be displayed while content blocking is active. This can be disabled, which should improve performance.

The reason why ScriptSafe performs the best is that it blocks JavaScript by default.

Other findings

The researchers also analyzed storage usage and the impact on browser functionality.

  • 86.6 percent of Chrome extensions use less than 10 MB of storage space.
  • 2.2 percent of Chrome extensions use more than 50 MB of storage space.
  • 6 extensions with more than 1 million break back/forward cache: LastPass Password Manager, Avast Online Security, Avira Browser Safety, Norton Password Manager, Snap & Read, Microsoft Editor.

Closing words

The installation of browser extensions may affect the processing and loading of websites. This has been known for some time, but is still important.

Content blockers improve both metrics, as they prevent primarily JavaScript-heavy content from loading in the first place.

Some extensions can delay website loading by 1 second or more. While this is the exception, users running these may want to consider finding alternatives that have less impact.

Another useful option is to restrict extensions from running on certain sites or only ‘on click’.

And you? Do you use browser extensions? Do they affect website loading?


Chrome extensions can significantly slow down browsing (with one notable exception)

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Chrome extensions can significantly slow down browsing (with one notable exception)


Browser extensions for Chrome can significantly impact website loading time and CPU processing, but there is one notable exception.


Martin Brinkman


Ghacks technology news



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