LMDE 5 on ProxMox high CPU usage on locked screen

[Zul716]

Greetings,
Running LMDE 5 on ProxMox I see constant 10 - 15% cpu utilization when on locked screen. If I ssh from another machine I can see that the process that is using cpu is "cinnamon --replace" (4 -5 instances). As soon as I unlock the screen, the cpu usage drops below to 1%. VM has 4 cores @ 3.6GHz
This isn't a big problem when running one VM, but could become when running several.
Could this be a problem with screen saver app? Or this happens only when running in a VM, since I do not recall seeing the same behavior when running on metal?
For the time being I disabled screen saver and cpu usage stays low.