So today I just troubleshooted the issue as I would any Moodle performance problem. I changed Apache mpm from prefork to event. I increased the max execution time and post max. I increased the memory. Etc. I then pulled the PHP code out of the WS and into a standalone PHP CLI script (hooking that into my Moodle so I could use the Moodle $CFG). I ran it from the CLI and found a few warnings. After fixing all of these things the WS works. It within a few ms downloads the tabulated data for all 16,000+ users using cURL and writes it to a file. Hope this helps someone else.
Web services
503 Service Unavailable
This discussion has been locked so you can no longer reply to it.