As per Ruediger, I'm forwarding this issue to the APR development list.

This thread goes back some time on the httpd development list.  The problem is that Windows takes about 1 second to reject attempts to connect to a dead port, leading to serious performance issues with sparsely populated load balanced proxy port banks.  The httpd folk added a connection timeout that can be specified in milliseconds in 2.2.11, but using this had no effect on Windows.

Previously on the thread [http://marc.info/?l=apache-httpd-dev&m=122358323701009&w=2],  Matt Stevenson had suggested doing
  apr_socket_opt_set(newsock,  APR_SO_NONBLOCK, 1);
before the APR connect call and
  apr_socket_opt_set(newsock,  APR_SO_NONBLOCK, 0);
afterwards, but this had other side-effects and testing (possibly all on UNIX platforms) indicated that this was not necessary for proper behavior of apr_socket_connect().

Unfortunately, what I'm seeing now on Windows is not proper connection timeout behavior.  I haven't added the changes suggested by Matt Stevenson to see if they help yet, but I plan on doing so.

Other suggestions and investigation of this would be much appreciated.

--
Jess Holle