An updated Google Webmaster Help thread has confirmed reports from Google's "sreeram" that Google is updating the Site Performance reports in Google Webmaster Tools.
During this update, Google has temporarily stopped updating the existing reports. The Googler said:
We are making some changes to the algorithms and pipeline behind the site performance feature and so had stopped updating it for a bit. We'll resume the updates soon, hopefully within a day or two. Do stay tuned and keep giving us feedback.
One new feature I am expecting is a trustworthy indicator to be added to the tool. I also suspect the tool to update more frequently and possibly offer better explanations of what can be improved.
Forum discussion at Google Webmaster Help.
