ANSWER:

You can try looking to see if you have the Output Caching module active. I have output caching enabled for images (.png) and saw a result of 0 msec just like your screenshot on subsequent runs.

The first result (uncached): 16 msec

The second test run (cached): 0 msec

The parameters for FRT I had enabled were: All Content (*), Status Code=200, Providers (all default).

ps. Try clearing your browser cache and do an “iisreset” from the command prompt and see if it updates.

by invulnarable27 from http://serverfault.com/questions/380477