In the meanwhile you were doing some real bughunting... I've found a temporary workaround for my situation. Not the best solution but i installed tinyproxy on the client-side and the problem disappeared. This workaround is only for the client i am working on.
I changed the code you suggested and it works! Man, you did it!
None of us with common sense wants a bloated apache webserver and writing rules for modsecurity only serving Dokuwiki on a home brewed machine. We have Hiawatha for this...
Is it possible that this bug(s) is slowing down the performance of Hiawatha?