If the Webmaster Tools site performance chart is any indication, that's exactly what they'll do. Let's just hope they'll ensure a large enough sample before usi

If the Webmaster Tools site performance chart is any indication, that's exactly what they'll do. Let's just hope they'll ensure a large enough sample before using this as a factor in search ranking. In my experience the Webmaster Tools performance indicator is terribly inaccurate for small sample sizes (relatively unpopular sites). For one site I have intimate details of, Googlebot visits roughly one page every three minutes. I have every indication (knowledge of what the site is doing, local and distributed load testing, analysis of server logs, etc.) that the site performs consistently and well, but the Site Performance chart on Google's Webmaster Tools is all over the place: anywhere from 0.4 seconds to load (99th percentile) (which is where it happens to be now and is probably slightly overestimating the site performance) to more than 9 seconds to load, oscillating pretty wildly. I'm fairly confident this isn't accurate (unless GA, the only external component on the site, is itself to blame). On other, more heavily trafficked sites the Web Performance chart seems much closer to reality--in line with our load test results and anecdotal experience, so whatever the issue is it seems to pan out when they take a large enough sample size. Edit: I see in other comments here that Google is using end-user data from the Toolbar to track this. That's helpful information and may explain the variability I and apparently others have seen. Again, this is a good reason to hope they'll only take this into account for large sample sizes. Otherwise, hope that your customers aren't using dialup connections.