Reecently, I had experience on problem configuring Apache 2.2.6 with Weblogic 11.3.5: when weblogic responded to apache mod weblogic with Status 304, the mod_wl slept 34 secs before to propaget the 304 response to the browser.

Please note 304 Status occurs if the resource was "Not Modified"

"If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server SHOULD respond with this status code. The 304 response MUST NOT contain a message-body, and thus is always terminated by the first empty line after the header fields."

We solved the issue upgrading the mod_wl to the latest weblogic module version.

http://docs.oracle.com/cd/E14571_01/web.1111/e14395/apache.htm