Remember which send_request_cgi can specify a timeout, which by default is 20, which is a long time. If server isn't answering in this time, the timeout for send_request_cgi can be increased, even when I think 20 is more than enough.

If this sleep tries to solve any issue with the threading, when doing too many requests to the server, then my feeling the problem shouldn't be solved with sleep, should be solved by adjusting the threading.