Test with ethernet to know if the issue is wireless or slow speed of windows writing to the TC..
Apple change the SMB for unknown reason and it has been causing trouble since Lion.. if your TC is older one.. take the firmware back to 7.5.2 as it is much better with windows..
Ensure your TC, wireless and disk name are all smb compatible.. ie short, no spaces.. pure alphanumeric.
Use WPA2 personal security for wireless.. fix the wireless channel and test 1, 6, and 11 for the best and fastest.
I downgraded the firmware and change my wifi setup to a roaming network. Further more i changed my workgroup in windows to the same workgroup name as in the TC and TE. Al this help a lot on the problem. What actually did the trick i don't know but problably they all helped a bit.
So thanks a lot for your input.
The one I forgot is bonjour for windows.. or the full airport utility for windows.
Anyway the issue is basic setup.. so much is designed purely for apple networking.. so the compatibility with windows is compromised.. not that apple would care.
I agree what actual bit is the key.. not sure.. it is better to fix it all so the TC actually complies with SMB rules.