I am also having the same problem. I have upgraded Qcad about three times this year with same issue. I am on Windows 7, Qcad version 126.96.36.199. Mapped network drive is accessed by three Windows 7 computers and they all have the same issue. I access the NAS drive with only one Qcad at a time. Sometimes takes 1 minute to read and/or write to the network drive. Other apps that I use (Draftsight, Adobe Illustrator, Photoshop, etc.) read/write very quickly to NAS as normal.
Qcad reads/writes normal speed to local drive. Can this PLEASE be addressed?