Sometimes the HTTP server gets in a state where it serves a web page made up of tiny packets, with some containing as few as 2 bytes. Consequently the page comes up slowly in the browser.
If I reset the board, the problem goes away. I haven't figured out how to reproduce it predictably.
These packets come very close together. I thought the HTTP server used delayed ACK?
Looks like my fault. The task with cgi_func() was starved for processor time, so I guess it was producing a small amount of data within 100mS. In any case, when it gets more cpu cycles, the speed of the web page is normal.
Thanks Dave