1. The client and the server are communicated over the network; therefore, check the network first.
2. After the user sets the checksum offload property of the VM NIC to off, sets DNS IP address of the NIC to null, disables the netbios function of the NIC TCP/IP address, the fault persists.
3. Open https://www.google.com.hk/ and enter oracle slow windows 7, the following case is found: http://odenysenko.wordpress.com/2011/10/28/slow-oracle-net-from-windows-7vista/