Maybe the CGI script is having to look up where the ESB (whatever the heck that is) is located before it can post to it. This can cause the 10 second delay you're mentioning if the nameservers lag. I had the same problem on my DSL for a while. If you can access the ESB (again, what is that?) directly without lagging, I'd try figuring out what the CGI script is using for nameservers.
Can the script post to other things without lag? Or does it lag period?