Performance Impact of Chrome Extensions on CPU, Rendering, and Memory

Recent observations of frequent Chrome crashes prompted an investigation into the performance impact of browser extensions. By testing 1,000 popular extensions across different sites, the study measured CPU usage, rendering delays, and memory consumption.

CPU Usage : Extensions such as Evernote, LastPass, and Dark Reader significantly increase CPU time per page, with Evernote adding 368 ms per page and Honey adding 825 ms on e‑commerce sites. Some extensions, like UberAgent, Dashlane, and Wappalyzer, caused over 20 seconds of CPU activity on a news article.

Rendering Time : Extensions can delay First Contentful Paint; Dark Reader increased Apple’s homepage load from ~1 s to ~4 s, while Honey added ~0.5 s on e‑commerce pages. Background activities of extensions like Avira Safe Shopping also contributed to delays.

Memory Consumption : Extensions increase per‑page memory usage and have their own memory overhead. Ad blockers and privacy tools, despite reducing network requests, can add up to 300 MB of memory (e.g., Trustnav). Overall browser memory usage dropped from 574 MB to 260 MB when ad blockers were disabled.

The cumulative effect of multiple extensions was evident, with combined CPU tasks causing noticeable slowdowns. Optimizations in newer Chrome versions reduced some impacts, but many extensions still add measurable overhead.

Key findings include:

Popular extensions can add hundreds of milliseconds to CPU time per page.

Rendering delays vary by extension and site, sometimes adding several seconds.

Memory overhead from extensions can be substantial, especially with ad blockers.

Performance improvements in newer Chrome builds may mask extension inefficiencies.

Overall, the study highlights the importance of monitoring and managing extension usage to maintain optimal browser performance.