Slow network problem

Dear all,

At the moment I'm running a CURRENT snapshot from February, yet  
somehow my network speeds are quite low. I've tested this with iperf,  
SMB and SCP, yet all give me more or less the same speeds, which is  
about 50 - 60Mbps. The weird thing is that this is only the case when  
the FreeBSD machine receives data, sending data is all fine. At least,  
with a 100Mbps link iperf gives me quite decent speeds (>90Mbps)

This is the case for gigabit as well as 100Mbps, depending on what  
cable I use to the switch.
I've also tested this directly, with a cable to a machine, but this  
was to no avail. I've tried changing some variables with sysctl  
(net.inet.tcp.recvspace, sendspace, recvbuf_auto,  
kern.ipc.maxsockbuf), yet those did not do anything.

dmesg has this to say about the network card:
rgephy0: <RTL8169S/8110S/8211B media interface> PHY 1 on miibus0  
rgephy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT,  
1000baseT-FDX, aut

I cannot say I've tested this with a STABLE release, but in Windows  
and Gentoo Linux this worked fine.

I have found one person with a seemingly similar problem, but this  
person had the problem a couple of years ago and did not resolve it at  
the time, or so it seems. See http://kerneltrap.org/mailarchive/freebsd-hackers/2006/5/30/214298 
  for his thread.

I hope someone can give me some tips that will solve this problem. If  
information is lacking, please do say so.

With kind regards,
	Sebastiaan van Doesselaar