rsync over ssh, slow speed (700 kB/s) on x230

Hi,

on my x230 the rsync over ssh speed is extremly slow - about 700 kB/s
over wireless. I don't see a performance issue on the source and target
systems. When I reboot to Linux the speed is acceptable - about 12 mB/s
over wireless.
The compression an ciphers parameters don't have impact to the speed.

Interesting is that under OpenBSD in debug mode the lines get printed
slowly.
692.05kB/s 0:17:16 debug2: channel 0: rcvd adjust 32768

Under Linux the debug lines scroll really fast over the screen
debug2: channel 0: rcvd adjust 114688

Do you have any ideas how I can solve the problem?
ulimit, openfiles limit etc. don't show any problems.

Thanks and best regards,
Sven