Google seems to have been adding new alerts or messages sent via the Google Message Center in Webmaster Tools. We saw an alert for high bandwidth access rates and now I am seeing reports of messages warning of "high response times" within your Sitemaps. The message reads:
Subject: "Some URLs in the Sitemap have a high response time."
Description: "Some URLs listed in this Sitemap have a high response time. This may indicate a problem with your server or with the content of the page."
In these reports, Google may tell you the average load time they see on your site. For example, a WebmasterWorld member said he was told he has an "average load time is about 1.1 seconds. The one page the singled out seems to take about 2.0 seconds to load." So, it seems that Google will list out the URLs that load slowly and give you a time associated with the load. I do not have screen shots of this in action.
I did find a confirmation from Googler, JohnMu, at a Google Groups thread from about a month ago. John said,
You might want to check your crawl rate graphs to see if you can spot any periods of high latency. We moved them to the "Statistics" section, under "Crawl stats." If you feel that we're crawling your site too quickly, you could set the crawl rate to "Slower" instead of "Normal."
This some what implies that Google is noticing a slow response time from the site and Google actually recommends, in some cases, that Googlebot might be causing the site to load slow. So he recommends that you slow down your crawl within webmaster tools, the set crawl rate feature.
Google Web Search Page Load Time Factor It is interesting that this seems to be a fairly recent error message from Google. The interesting part is, I believe, that it was released about the same time Google AdWords released page load time factor into the quality score. Could Google be using the same metrics for this statistic on both Google AdWords and Web Search? Possibly.
Forum discussion at WebmasterWorld.