@Olsen
Thank you for your suggestions. This is getting strange . let me try to explain and see if i did it right.
tcp.sendspace is set to 32768 now (don't know what it used to be) and that didnt improve the speed.
increasing the writerequests setting did help! but i have to set it to insane high numbers before the number of requests is'nt identical to the max value.
I set it to 15000 and tested tcpspeed and now i can get 1706 kB/s

i had a maximum of 14067 in use then.