Apache was too busy dealing with web requests, and could not process cgi
requests until traffic subsided. Perhaps Perl/cgi requests are lower
priority?
I think it's more complex than that, but serving simple html files takes less time, requires less memory, can more easily be cached and so on. If your server is running at 99% CPU capacity or 99% RAM or whatever, it's more likely that errors will occur with dynamic than with static files, surely?
