excel 2007 saves files very slowly to a mapped network drive

[HipHoper]

HI,

I configured a client's network this weekend to work with shared folder protected by windows login password to enhance his office security.
The first computer I've changed the windows login to a one with a password gave me "explorer.exe server execution failed" and I fixed it by changing the registry of personal folder to a local drive.
I'm experiencing slowness in saving office 2007 files to a mapped network drive. Locally it saves fast.
I've tried :
1. disconnect from all network drives and then reconnecting them
2. disabling avg free 2013 AV
3. Restored documents folder to its orginal location and the according registry settings

Any suggestion ?

Thank you