Author here. Most of the negative performance impact comes running the injected JavaScript code, so it will be the same on all websites. I tested different sit

Author here. Most of the negative performance impact comes running the injected JavaScript code, so it will be the same on all websites. I tested different sites in 2018, but it's harder to see the performance impact of an extension, because variability between tests is larger for more complex pages. https://www.debugbear.com/blog/measuring-the-performance-impact-of-chrome-extensions https://www.debugbear.com/blog/measuring-the-performance-imp... Generally the site you're on doesn't matter. Ad blockers are different, since they have a positive impact on sites with ads. Some extensions are site-specific, e.g. Wikiwand. I'm also mentioning Avira as a special case. If I tested each extension on the top 1000 sites I could identify more examples, but don't think it's worth the effort/cost. > The assumption one might make is that these extensions stack up but I could imagine there could be non-linear effects combining extensions (unless there’s prior research indicating it is linear in all or almost all cases?). Yeah, if you different extensions add more JavaScript bundles the performance impact just adds up. I've not looked at this in depth, but the 2018 post takes a quick look at combining multiple extensions. https://www.debugbear.com/public/blog/chrome-extension-performance/all-extensions.png https://www.debugbear.com/public/blog/chrome-extension-perfo...