https://xx.xx.xx.xx/iControl/iControlPortal.cgi?WSDL=LocalLB.Pool directly in browser takes 45 seconds

All requests through the iControl portal are queued so it could be if you have another iControl request that is long lived coming in right before your WSDL request, it could theoretically delay the WSDL request until the previous request completes. The WSDL request is just a file read out of a resource so I can't see why that would cause a 45 second delay aside from the above guess. I would recommend downloading the WSDL and either precompile it into your app or load locally if it's present if possible.

-Joe