I ran the tests 7 times and then took the median. I'll look into quantifying variance more, but for now here's a boxplot for total on-page CPU time. https://gis

I ran the tests 7 times and then took the median. I'll look into quantifying variance more, but for now here's a boxplot for total on-page CPU time. https://gist.github.com/mattzeunert/de3c8aedd2936a34eeb88b62b985ff13#gistcomment-3343338 https://gist.github.com/mattzeunert/de3c8aedd2936a34eeb88b62... I ran tests on example.com, apple.com, and a WCPO news article (for the ad blocker tests). The biggest performance issue is that extensions just dump large scripts into pages indiscriminately. Most of the time extensions don't do anything differently based on the content of the page. I also tested a WCPO news article to see the impact of ad blockers. I picked a local news website specifically because they contain a lot of ads. If a page doesn't have any ads the performance impact of an ad blocker will be slightly negative. What my tests don't pick up is extensions that only run a certain domains. For example, if you run Honey on a shop they support I expect the CPU consumption to increase a lot more. I wrote a similar article last year, which tests a few other pages as well: https://www.debugbear.com/blog/measuring-the-performance-impact-of-chrome-extensions https://www.debugbear.com/blog/measuring-the-performance-imp...