Guest NIC Speed and copy from host to guest

   Hello to all, I have a Windows 2012 host and started a copy today from the host to another VM that works as File Server that is also a Windows 2012. The rate is very slow, something around 10 Mbps, physical NICs are configured as auto sense and can reach 1 Gbps.

   Questions:

   1- Should I set a value (customer switch operates at 100 Mbps) on physical NICs, i.e. remove auto-sense and insert 100 Mbps for example?

    2- If I'm not wrong, a long time ago (virtual server or PC) one could quickly copy files from host to guest through special "extensions" on the guest, is it still possible? 

    Any special recommendations to increase NIC rate on guest OS?

    Best regards, EEOC.