Windows 10 Virtual Machines running very slow in Hyper-V Server

sglee used Ask the Experts™
 I am running into a situation where Windows 10 virtual machines in Hyper-V servers are running so slow. In the same servers, other virtual machines running Windows Server 2012 or Windows Server 2016 operating system are running as fast they can and very responsive.
 But on three separate Hyperv-V servers, Windwos 10 virtual machines are extremely slow even if I assign like 8 to 12GB of RAM (when it does not need more than 4GB). I allocate about 40-50GB of total space to these and they have about 20GB free space and they all have 1 vCPU assigned.
  Where do I need to check to find out what is slowing down these Windows 10 virtual machines?

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Dr. KlahnPrincipal Software Engineer

Bring up Task Manager on both the host and in the VMs, and see if something is monopolizing the CPU or vCPUs.
Technical Architect - HA/Compute/Storage
Flip the vCPU count up to 2 to start. One is too restrictive thread count wise.

vRAM at 4GB is more than enough so long as they are not running something that causes the VM to use swap file.


There are only 6 vCPUs on this server and there are already 5 VMs. Is it ok for the total number of vCPU assigned to VMs to exceed that of vCPU count?
Philip ElderTechnical Architect - HA/Compute/Storage

6 physical cores?

Yes. CPU is seldom the limiter. It's almost always the storage subsystem that limits performance with physical RAM being a distant second.

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