How to optimize the following performance issue ?

Hello ,

My performance validator tool suggests the following optimization tip that i could not able to figure out.

The following resources have identical contents, but are served from different URLs. Serve these resources from a consistent URL to save 1 request(s) and 25.2KiB.
http://static.ak.facebook.com/connect/xd_arbiter.php?version=11
https://s-static.ak.facebook.com/connect/xd_arbiter.php?version=11

Can you tell me which part of your script causing this and how could i solve this ?