as described in  webpage loading as www.lastlog.de in konqueror is very slow. as also written in  a solution is to set the dns server in /etc/resolv.conf NOT to the fritz!box (or whatever router you might have) but to the DNS server directly.
in  user "army" says that it's a problem with  but here it seems konqueror produces much more DNS requests as any other browser. And more interesting: konqueror with direct DNS entry in /etc/resolv.conf vs konqueror with direct DNS settings (DNS-proxy from fritz!box) is showing that there is a massive DNS request difference as in the first case will produce less DNS requests as in the later setting where it seems to flood the link with 'say' already answered requests. NOTE: see  for futher reading.
i finally installed a proxy on my local computer.