Why extensions slow Chrome down, and which ones to suspect
Extensions do slow Chrome down, but not evenly, and not in proportion to how many you have. One badly behaved extension costs more than a dozen well-behaved ones.
What actually costs you
The expensive thing is running code on every page you open. An extension with access to every site injects its script into every tab, and does that work again on every navigation. 30% of the 49,702 extensions we examined have that access — which is also why narrowing site access is the single most effective thing you can do.
The second cost is memory. Extensions built on the current platform run their background code only when needed and shut down afterwards. Older ones kept a page resident the whole time Chrome was open, which is part of why the platform changed.
Finding the one responsible
Chrome has a task manager: Shift+Esc on Windows and Linux, or Window then Task Manager on macOS. Extensions appear by name with their memory and CPU use. Sort by CPU and open a few pages; the one that climbs is your answer.
For a slowdown that only happens on certain sites, open that site with extensions disabled in an incognito window, then re-enable them one at a time.
What to do about it
- Narrow the site access rather than uninstalling. Set it to run on click, or only on the sites where you need it. Most of the cost disappears with it.
- Remove what you no longer use. Not for speed — an idle extension costs little — but because it still holds whatever permissions you granted it.
- Check the ones you have not thought about in a while. An extension that has not been updated in years is not being optimised either. We keep a list of the ones nobody has touched in over two years.
The count is the wrong thing to look at
Advice to "keep it under ten extensions" is not useful. Ten narrow-scoped, actively maintained extensions will cost you less than one that runs everywhere and has not been updated since 2021. What matters is what each one is allowed to reach, which you can look up on our check page.