the performance impact of the most popular extensions




There are few as important to many browser users as browser extensions, and in that regard Chrome for many years that can boast of having more than any other.



However, these can be a double-edged sword, because although in most cases they offer us extra utility, they also do so by increasing the consumption of resources of a browser that is already more than famous for it. It is something that this DebugBear report makes clear after analyzing the performance impact of the 1000 most popular extensions for Google Chrome.



Using the CPU and consuming memory like there's no tomorrow





Chrome Extension Page Cpu Time


CPU time per extension when loading a page (example.com) - DebugBear.com



DebugBear analyzed four different metrics: page CPU time, page rendering lag, background CPU time consumption, and browser memory consumption.



It explains that when JavaScript is executed (what the extensions are written in) the main browser thread is blocked, which means that it cannot respond to user interactions.



When no extension is installed loading a page like example.com takes about 40 milliseconds of CPU time, while if you have installed an extension like Evernote or Grammarly the time increases to more than 500 milliseconds.




Evernote Web Clipper is the most popular extension that uses the most additional CPU usage, almost 12 times more than in a Chrome without extensions




The list of the 20 slowest extensions of the 100 most used, that is, those with several million installations in the Chrome Web Store, includes: Evernote, Grammarly, Avira Password Manager, Flash Video Downloader, Dashlane, Office, Avira Browser Safety, LastPass, AVG / Avast SafePrice, Skype, AdGuard AdBlocker, Norton Password Manager, Ghostery, and more.







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If you notice something they have in common, it is that many are security solutions from antivirus companies or password managers. This is explained in some cases because extensions tend to inject code into each page the user visits rather than a specific one. A password manager has to see if there are login forms on each website for example.



However, not all extensions need to do that and they also don't need to load all the extension code just to check the relevant conditions. DebugBear suggests that to improve performance you could choose to separate the primary functions of the extension so that the code is loaded only if necessary.



For more than a few milliseconds sound like nothing, we must take into account what happens when we accumulate pages and extensions, everything comes together and in the end the impact on performance ends up being much greater for the user, especially if they have many extensions and many open tabs.






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Entry 2020 06 16 134 750


Chrome Extension Performance Lookup - DebugBear.com



In the case of memory consumption Avira stands at the top of the list increasing memory consumption by 218 MB, closely followed by Adblock Plus, AdBlock, AdBlock and Omega Adblocker.



In terms of background CPU usage, much the same is true, Avira top by far followed by various ad blockers. The thing is, most adblockers work by blocking network requests that the page starts, and to decide which ones to block they need to do some background processing.



What happens many times is that although an adblocker can reduce CPU time on the page by blocking items, it can also increase it in the background just by deciding what to block. Ironic.





Ad Blocker Bg Cpu


Background runtime when loading an article from different adblockers - DebugBear.com









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DebugBear analyzed 20 privacy blockers and tools like DuckDuckGo Privacy Essentials, uBlock Origin, Ghostery, Privacy Badger, Adblock Plus, etc. and found that although several reduce the CPU time on the page they also increase it in the background depending on how many expressions they have to check.



In terms of memory, although the adblocker consumes a lot by running in the background, this is usually compensated greatly by reducing the memory consumption of the page, as long as the page has a lot of ads. The dilemma is that on a page with no ads or almost no ads, sometimes the blocker consumes more browser resources just to be there.



Not all work the same, tools like DDG Privacy Essentials, uBlock Origin, and Privacy Badger suffer almost from this problem, but many other adblockers including famous ones like Adblock Plus and Ghostery do add their weight to the CPU.



More information | DebugBear