Investigating the Influence of 5,000 Chrome Add-ons on Performance

DebugBear website performance monitoring service published results of an analysis of the impact of browser add-ons on the performance and comfort of users. The study tested 5,000 of the most popular Chrome add-ons. The testing assessed the CPU load, the amount of downloaded data, page loading speed, delays when user interacts with web pages, and disk space consumption.

Some conclusions:


  • Using add-ons with ad blockers typically reduces CPU load, reduces the amount of data downloaded, and reduces memory consumption. For example, the uBlock Origin add-on, which has 37 million users, reduces CPU load from 57 to 4 seconds. when viewing pages on one of the news sites with an abundance of advertising. At the same time, the reduction in CPU load when using the most popular blockers AdBlock (66 million users) and AdBlock Plus (45 million users) turned out to be minimal and did not exceed 15%.

  • When assessing traffic savings when blockers are enabled, the best performance was demonstrated by uBlock Origin, which reduced the size of downloaded data on the tested sites from an average of 41 to 3 MB. The ScriptSafe add-on was ranked higher, but this was achieved by completely disabling JavaScript.

  • When testing the impact of add-ons on memory consumption, the DuckDuckGo Privacy Essentials add-on had the best results.

  • Of the 336 add-ons with more than 1 million users, 11 resulted in an increase in processing of each page by more than 0.5 seconds. CPU time. The worst performance was observed for the Monica add-on, which has 2 million installations – when used, an additional 1.3 seconds were spent processing each page. The Read&Write add-on, which has 17 million installations, took 0.8 seconds of CPU time.

  • Repeating the test on the Ikea website made it possible to identify add-ons that slow down the work and solve problems specific to online stores. For example, the Honey add-on, which has 20 million users, created a delay of 1.5 seconds. CPU time.

  • When expanding the test to 5,000 of the most popular add-ons, the worst performance (2.3 seconds of CPU time) was found in the MaxAI add-on, which has 800 thousand users.

  • When testing 5000 add-ons on the Ikea website, the worst performance (almost 5 seconds of CPU time) was found for the “superagent – Automatic cookie consent” add-on.

  • 86% of the tested add-ons created a minimal (less than 50 ms) load on the CPU, 5.2% of add-ons created a load of 50 to 100 ms of CPU time, 4.4% – from 100 to 250 ms, 2.4% – from 250 to 500 ms, 1.7% – more than 500 ms.

  • Testing page loading slowdown (metric FCP, First Contentful Paint) showed that there is no direct correlation between high CPU load and page loading delays. For example, the processor-intensive add-ons Coupert Coupon Finder and Merlin AI did not slow down page loading. Among the add-ons that slow down page loading most significantly are Monica AI, Klarna and Avast Safeprice, which launch handlers when loading begins, and not after it completes. Slowness also occurred when using add-ons that offer VPN access.

    A selection of add-ons with over a million users:

    A selection of the 5000 most popular add-ons:

  • Testing latency when working with pages (metric INP, Interaction to Next Paint). Among the add-ons with more than a million users, Avira Password Manager stood out, which introduced a delay of 160 ms with each mouse click (the delay only appears for the first 5 seconds, until initialization is completed). Using the Microsoft Editor extension and Superb Copy added delays of 10 ms.

  • Of the 5,000 add-ons tested, 27 caused more than 100 MB of disk space to be consumed. The leader was the Meme Soundboard add-on, which required 600 MB due to storing 723 MP3 files.

  • 87% of add-ons are less than 10 MB, 11.2% are more than 10 MB, and 2.2% are more than 50 MB.
  • 1.7% of add-ons block caching of transitions between pages (back/forward cache). Such add-ons include: LastPass Password Manager, Avast Online Security, Avira Browser Safety, Norton Password Manager, Snap&Read and Microsoft Editor.
  • Pre-loading and pre-rendering are blocked by 8 add-ons (0.2%), including uBlock Origin, Windscribe and Privacy Badger

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