Hi,
Could you post the VM config? (cat /etc/pve/qemu-server/<VMID>.conf
)
Unfortunately, it's likely not be a case that CPU usage is high, but rather, the processing power you have available is just too limited. Trying to have two operating systems (proxmox + parrotOs) share just two cores is quite a stretch, however minimal both these systems might me. This is also true for 4Gb of ram. However by assigning ParrotOs less resources, it may be able to run better.