PageSpeed Insights' analysis does not use real devices. PageSpeed Insights
fetches a site with a Blink renderer (the rendering engine that powers Google
Chrome) that emulates both mobile device and desktop devices.
I changed my site! Why doesn't PageSpeed Insights see
the new version?
PageSpeed Insights caches results for a short period of time. PageSpeed
Insights should see any changes you've made within a few
Where do the PageSpeed Insights performance optimizations come
Many of the rules used by PageSpeed Insights came out of recommendations
of blog posts and articles published by developers in the web community.
Other rules were added by developers at Google based on research and internal
use by Google applications.
PageSpeed Insights recommendations seem to conflict with the
guidance I am getting from other site speed optimization tools. What should I
We would like to learn more on where you saw a discrepancy between the
tools. Send a message to our
Some of PageSpeed Insights' recommendations seem
against certain design and development practices. Does Google think
that only speed is important?
Since PageSpeed is a performance optimization tool, its
recommendations are biased in favor of speed.
However, we recognize that web development is complex, and our
suggestions might be restrictive for an individual web site.
You have to consider the tradeoffs for your own application: some of
PageSpeed's recommendations take substantial effort
to implement, so you need to evaluate the cost of making changes vs.
the benefit the rule would have on your page.
Our goal is simply to point out the issues that you should consider
Are PageSpeed Insights' recommendations more
applicable to Google's applications than to the average website?
No. The advice given by PageSpeed is not specific to
Google; it should improve the performance of any web page. Of course,
pages that are slower have more to gain from PageSpeed's
Why am I seeing a captcha?
PageSpeed Insights may occasionally show a captcha to confirm you are not a bot.
If you are encountering a captcha when using the API, it may be due to the fact
that you are using a shared API key. You can acquire an individual API Key by
Does the PageSpeed Insights score represent the
real-world user experience?
PageSpeed Insights checks to see if a page has applied
performance best practices but does not account for all the factors that
can affect a page's speed - e.g. type of the device used to access the page,
network speed, and cache reuse of shared resources. As a result, while the score
is correlated with the speed of a page, it is not completely representative of
the real world user experience.