Passing CC2531 USB Device Causes High CPU in VM

I’m running unRAID and using KVM as the hypervisor. I need to pass the following device to a Hass OS VM (Home Assistant):

“Texas Instruments TI CC2531 USB CDC (0451:16a8)”

The device is a USB CC2531 dongle flashed with zigbee2mqtt firmware which the VM sees as /dev/ttyACM0.

Is sees the device but cpu a lot higher than without the dongle. Without the dongle passed the qemu-system-x86 process for this VM consumes approx 25% cpu, when attached to the VM the cpu rises to 150%.

I know this sounds more like a hypervisor issue but any thoughts here from others would be appreciated.

I really don’t have any pertinenent logs or any. I’m on 6.8 stable and the VM is using Q35-2.11.

Any advice thoughts here will be greatly appreciated.