Slow I/O on a Windows 7 Host

[Bob J]

I have a Windows 7 host with a Windows 10 Desktop Image VM for the purposes of doing development work for a pre-release of Windows 10 Physical desk tops. The Windows 10 VM can be very slow at times and by the looks of it, the I/O read writes are hitting a bottle neck. I can see the Read is maxing at @ 15 MB/s and the write is maxing out around 5 MB/s.

For the VM, I have a SATA Controller, that has a .VDI file for the HD. It is a fixed size of 250 GB.

Any help would be greatly appreciated to finding out why the VM has very slow I/O.