cygwin rsync over ssh very slow

Question

I have 2 machines running Windows Xp SP3. I have cygwin installed on both, version 1.7. I have rsync and ssh installed on both, and configured using default settings as per ssh-host-config and ssh-user-config programs provided.

I moved the public keys into their respective locations, and basically ssh is working fine. i began an rsync operation, using:

rsync -av --delete --hard-links local_dir username@other_machine:/some_dir

well... on both machines, the processor is running near idle, no heavy usage. I checked IO using process explorer on both machines, and that too is at normal levels (1~2 MB/s), so I can't see where the bottlenecks are, because network performance is aweful. I'm not going over 1MB/s... when a normal file copy using windows sharing achieves some ~10 MB/s..

What could be wrong?

edit1:

As suggested, i ran an iperf test, with not-so-good results at all...

$ iperf -c 192.168.66.3 -t 10
------------------------------------------------------------
Client connecting to 192.168.66.3, TCP port 5001
TCP window size: 64.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.66.5 port 1220 connected with 192.168.66.3 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-17.0 sec  72.0 KBytes  34.7 Kbits/sec

Answer 1

I'd first try to find out if your networking (inside cygwin) is slow. You could try to use iperf to run some basic benchmarks.

On the server:

iperf -s

On the client:

iperf -c <host of server>

This should give output showing close to 100 MBit/sec. If not, the problem is unrelated to rsync (and the encryption you use because of the SSH access).