Linux KVM - Windows 10 VM - Mouse movement delay

These are the things I do to get the best overall performance (and interactive performance!) out of a Windows VM:

• Use a virtual CPU type as close to the host CPU as possible. Ideally set host-passthrough if live migration is not required.
• Use the Virtio-SCSI controller and SCSI virtual hard disks (not Virtio or SATA virtual hard disks). This requires providing drivers at install time but that's easy enough.
• Set the display to Spice (not VNC) and the video controller to QXL.
• Install the latest Spice Guest Tools in the VM. (This is probably what you missed.)

Installing Windows VM is sometime tricky. At least for having good performances.

When I install a Windows 10 VM I do as follows :

• 2 vCPU, 4 Go of ram.
  • for CPU, copy host configuration
• 1 Hard Drive image (qcow2)
  • disk bus Virtio
  • performances, cache mode writeback, E/S mode Threads
• Networking is set to virtio too

Before installation, insert this ISO (in addition of Windows ISO disk) The ISO

During installation, you need to add the following drivers to get it work properly :

• viostor
• NETKVM
• balloon

In your case, since you have already deployed your VM you need to install the exact same driver. But follow a special procedure because switching to virtio gonna break your VM.

By following the great tips of this thread you can fix this problem.

Here is a TLDR (AFTER INSTALLING THE DRIVERS) :

1. Open a CMD as admin on your VM and type this (to get in safe mode) :

   bcdedit /set {current} safeboot minimal

2. Shutdown the VM, switch storage and network to virtio.

3. Start the VM, it's going to boot into safe mode.

4. Open a CMD as admin and type this (to get back in normal mode):

   bcdedit /deletevalue {current} safeboot

Now you should be able to get a quick and smooth windows VM.

EDIT : Don't forget to install all spice tools. More infos here in the Windows section, get this installer