Re: 6.5.5 much slower than 6.3.6

> I've noticed, that the 6.5.5 trace contains alot of "getpid" calls,

As previously mentioned that should not be a problem.  The getpid() method
has nearly zero overhead.  We might be able to discern something from the
debugging log.  Add -debug all to your command line and forward the logs
(6.3.6 and 6.5.5) to this e-mail address.