Puzzled by increased CPU load

[ChrisCW01]

I am in the progress of migrating my virtual machines to a new server. When I am comparing the CPU load generated on the old server with the new server I see an increase of about 100%.

The same Win10 guest idling on the old server consumes about 20-25% CPU, on the new server this will be about 50-55%.

For a linux Ubuntu 20.04 guest it is 2-3% on the old server, on the new server it is around 5%. I have migrated the VMs using export/import.

Now I know that there are many factors playing a role but it is still puzzling.

Specs for the old server
- Dell T20 with Xeon
- 32 GB RAM
- VDI on SSD
- Ubuntu 16.04 with kernel 4.4.0-179-generic #209-Ubuntu SMP
- VirtualBox 5.2.42 r137960

Specs for the new server
- Dell T30 with Xeon
- 40 GB RAM
- VDI on SSD
- Ubuntu 20.04 with kernel 5.4.0-37-generic #41-Ubuntu SMP
- VirtualBox 6.1.10 r138449

Both environments are pretty similar with the new server having a bit better specs on the hardware side. That's why I am puzzled by the fact that the performance in terms of running VMs seems to be worse with the new server.

Any ideas what could cause this effect? I have attached log files for the Win 10 VM of both servers if that helps.

Kind regards,

Christoph