Zoomkat,
Your experience with server and Ethernet shield apparently is making you think it translates to arduino wifi shield. Last year I did quite a bit of work on wifi servers. The firmware is crap and server crashes too often and varies between different browsers. I agree with you to time each process. But if you still run the server code as if there IS NOTHING ELSE that matters, you will be bitten on the ars soon enough, even running Ethernet shield with a known good server firmware.
OP,
Your problem has always been trying to simultaneously run two programs that are only designed to run only by themselves alone. 99.9% of arduino programs and libraries are designed to run as if there were no other stuff going on. Running two programs simultaneously needs more than cleverly placing calls at the "right" location. It often requires rewriting the entire program, if not the entire library. You might "succeed" right now but watch out for freezes and non-responding servers and DON'T COMPLAIN!
I find myself useless in this discussion. I bit you farewell.