Source: http://forum.swsoft.com/printthread.php?threadid=40173

If qmail-smtpd is spawning many processes and comsumming all processing capacity on a server check the name of the *.pem files in /var/qmail/control. If the files are not:

 dh512.pem
 dh1024.pem

Rename them (usually I've seen dhparam512.pem and dhparam1024.pem) accordingly, or, symlink them: