Jeff answered a [question][1] over at M.SO in relation to why the SE network of sites are *so fast*.

The answer you are looking for (note that this doesn't mention SF, just "us", so I'm presuming all the sites.):

> Google's crawler is now indexing us at, and I am not making this up,
> **10 requests per second**, which is the maximum.

Lots of quick, topical, regularly updating content is working in SE's favour.

  [1]: http://meta.stackoverflow.com/questions/84695/eeeeek-where-is-my-slow-performance/84701#84701