The stock windows 1.25 clients are all about even, except for the GUI (Tray) version is a tiny bit faster. I haven't tried the multi-processor version yet.
I recompiled all of the windows clients and got a 1% increase on the GUI and an 8% increase on the comand line version.
So the fastest for windows right now is the recompiled comand line version. Which you can get below.
eccp109s.zip
copy the cygwin1.dll into Windows/System32/
and the rest into your client directory. The exe's are named different from the originals. So you can compare for yourself.