Firefox is not cache friendly

As it turned out, if the same uncached picture is requested several times during the page loading process, each time it will be loaded in a new way. At subsequent page loads, the picture will be pulled out of the cache and requests will be made correctly.

UPD: Explanation of the situation
All this will happen as a result of a forced reboot by Ctrl + F5.

For an example, you can look at the loading process of the yahoo.com website in the FireBug’s Network tab:



Or rivet an HTML file of the form: