Topic: meta: http-requests vs. mysql-requests


i currently wonder what is more expensive, to have

- 1 request with some DB-Action,
- 2 requests, 1 pagecache and 1 login-update via ajax.

the question is about serverperformance and client-performance.

New Relic : Scaling Rails - Podcasts shows the 2nd option, so i wonder, if the http-request does not matter in performance guidelines..

any comments?