>One day I thought outside normal frames, created for each VM a special directory
outside all VHD on the host machine, cut the RAM of each VM by more than half and
started & accessed all tables on the host machine. As no LAN wires stemmed data flow,
the host machine now had excess memory to buffer data access for all 3 VM and
this used the physical RAM much better than "fixed" RAM buffering the "local" vhd data.

>Benefit of buffering on host gave a stronger boost than piping the data through
TCP/IP stack without physical cables added as overhead....

But, IIRC, you had to employ the TCP/IP to access host machine from inside the VM, cableless and simulated probably, but still used. The overhead you avoided seems to be the emulated disk access inside the VM and its memory management.