copying from WinXP to Win7 slow while copying from Win7 to WinXP very fast

I tied to copy a large file from WinXP PC to Win7 PC (read from WinXP
share on Win7 PC), it's very slow, running at 10% of 100Mbps network
(as shown in task manager), while copying from Win7 PC to WinXP (the
same two PC) is very fast (write to WinXP share on Win7), at 90% of
100Mbps network. Why is that?

I haven't tried do the copying on the WinXP yet, the WinXP has issues
accessing the share on Win7 (which other Win7 PC can access). Need to
figure out this also, but not that important.

Thanks.

 

This guy could probably answer your question.

http://blogs.technet.com/b/markrussinovich/archive/2008/02/04/2826167.aspx

That is an example of the basic copy mechanism, but it doesn't cover the
effects of network tweaks (encrypted VPN as network), or the effects that
an AV product might have on the process (scanning the file as it is being
transferred, doubling the number of read operations). So other users
of those OSes, might not be seeing the same thing as you.

Paul