Third Party Web: an analysis of third-party script costs

Martin Brinkmann
Feb 15, 2019

Third Party Web is an initiative to analyze the cost of third-party scripts on websites to provide Internet users and developers with actionable information.

The project has four simple goals:

  1. Quantify the impact of third-party scripts that run on the top 1 million sites according to Alexa.
  2. Identify scripts that have the greatest performance costs.
  3. Provide developers with information.
  4. Incentivize responsible script behavior.

The project team runs two scans on about four million sites per month using Lighthouse on mobile to identify third-party scripts and the performance impact they have.

According to the data, about 65% of all script execution time is caused by roughly 800 origins; the top 100 origins account for about 59% of all script execution time on the analyzed sites.

Read also:  Extensions may impact performance.

The project sorts scripts into categories such as ads, social, analytics, or video to make it easier to compare the performance impact of related scripts.


The biggest offenders in regards to the average performance impact:

  • CreateJS CDN -- Libraries -- 3188ms on average
  • WordAds -- Advertising -- 2543ms on average
  • Popads -- Advertising -- 1245ms on average.
  • 33 Across -- Advertising -- 1170ms on average.
  • Wix -- Hosting Platforms -- 1153ms on average

All scripts, with the exception for the Wix script, which was found on more than 158k sites, were found on a relatively low number of sites (about 30,000 or less).

The biggest offenders in regards to distribution:

  • Google/Doubleclick Ads -- Advertising -- 1412404 executions, 330ms average.
  • Google Tag Manager -- Other -- 1093167 executions, 386ms on average.
  • Wix -- Hosting Platforms -- 158466 executions, 1153ms on average.
  • Facebook -- Social -- 1212567 executions, 120ms on average.
  • Google CDN -- Libraries -- 811231 executions, 178ms on average.

Advertisement and Mixed/Other scripts make up the largest chunk of third-party script executions.

It should not come as a surprise that scripts by major Internet companies -- Google and Facebook specifically -- are found on a large portion of scanned sites. Google alone has five scripts in the total impact top ten, with three of them breaking the one million execution barrier.

Google scripts were found in about one in three sites at a minimum, Facebook scripts in one in four sites.

Closing Words

Third-party scripts impact web performance significantly; a simple visual comparison of the loading performance of sites with and without content blockers is enough to highlight that fact.

The result of the study is not really that surprising: third-party scripts impact performance, and Google and Facebook have scripts running on a large portion of Internet sites.

Now You: What is your take on the study?

Third Party Web: an analysis of third-party script costs
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Third Party Web: an analysis of third-party script costs
Third Party Web is an initiative to analyze the cost of third-party scripts on websites to provide Internet users and developers with actionable information.
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  1. ilev said on August 4, 2012 at 7:53 pm

    Doesn’t Windows 8 know that www. or http:// are passe ?

    1. Martin Brinkmann said on August 4, 2012 at 7:57 pm

      Well it is a bit difficulty to distinguish between domains and files for instance.

    2. Leonidas Burton said on September 4, 2023 at 4:51 am

      I know a service made by google that is similar to Google bookmarks.

  2. VioletMoon said on August 16, 2023 at 5:26 pm

    @Ashwin–Thankful you delighted my comment; who knows how many “gamers” would have disagreed!

  3. Karl said on August 17, 2023 at 10:36 pm


    The comments section under this very article (3 comments) is identical to the comments section found under the following article:

    Not sure what the issue is, but have seen this issue under some other articles recently but did not report it back then.

  4. Anonymous said on August 25, 2023 at 11:44 am

    Omg a badge!!!
    Some tangible reward lmao.

    It sucks that redditors are going to love the fuck out of it too.

  5. Scroogled said on August 25, 2023 at 10:57 pm

    With the cloud, there is no such thing as unlimited storage or privacy. Stop relying on these tech scums. Purchase your own hardware and develop your own solutions.

    1. lollmaoeven said on August 27, 2023 at 6:24 am

      This is a certified reddit cringe moment. Hilarious how the article’s author tries to dress it up like it’s anything more than a png for doing the reddit corporation’s moderation work for free (or for bribes from companies and political groups)

  6. El Duderino said on August 25, 2023 at 11:14 pm

    Almost al unlmited services have a real limit.

    And this comment is written on the dropbox article from August 25, 2023.

  7. John G. said on August 26, 2023 at 1:29 am

    First comment > @ilev said on August 4, 2012 at 7:53 pm

    For the God’s sake, fix the comments soon please! :[

  8. Kalmly said on August 26, 2023 at 4:42 pm

    Yes. Please. Fix the comments.

  9. Kim Schmidt said on September 3, 2023 at 3:42 pm

    With Google Chrome, it’s only been 1,500 for some time now.

    Anyone who wants to force me in such a way into buying something that I can get elsewhere for free will certainly never see a single dime from my side. I don’t even know how stupid their marketing department is to impose these limits on users instead of offering a valuable product to the paying faction. But they don’t. Even if you pay, you get something that is also available for free elsewhere.

    The algorithm has also become less and less savvy in terms of e.g. English/German translations. It used to be that the bot could sort of sense what you were trying to say and put it into different colloquialisms, which was even fun because it was like, “I know what you’re trying to say here, how about…” Now it’s in parts too stupid to translate the simplest sentences correctly, and the suggestions it makes are at times as moronic as those made by Google Translations.

    If this is a deep-learning AI that learns from users’ translations and the phrases they choose most often – which, by the way, is a valuable, moneys worthwhile contribution of every free user to this project: They invest their time and texts, thereby providing the necessary data for the AI to do the thing as nicely as they brag about it in the first place – alas, the more unprofessional users discovered the translator, the worse the language of this deep-learning bot has become, the greater the aggregate of linguistically illiterate users has become, and the worse the language of this deep-learning bot has become, as it now learns the drivel of every Tom, Dick and Harry out there, which is why I now get their Mickey Mouse language as suggestions: the inane language of people who can barely spell the alphabet, it seems.

    And as a thank you for our time and effort in helping them and their AI learn, they’ve lowered the limit from what was once 5,000 to now 1,500…? A big “fuck off” from here for that! Not a brass farthing from me for this attitude and behaviour, not in a hundred years.

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