Windows 10 on Windows 10 with Core2Quad

[VoNa]

I'm trying to use Windows 10 (whatever@4 GB ram) on a Windows 1909 host using ASUS P5Q PRO with Intel Core2Quad 9550 (@3.61GHz) with 8GB ram (VirtualBox Version 6.1.6 r137129 (Qt5.6.2)).
But the performance is just crap! Host is showing up the useage of 2 cores at max, it is much slower than using just 2 cores - it is taking ages longer with all cores, also if I'm reducing the percentage down to 75% for CPU. Host will use just 50% of the power and guest is fu..... slow - same with 3 cores.
My feeling would say, the factor for 2 core:4 core is about 20:1 - at the moment it is useless to use more than 2 cores. No difference between fresh install or just changing the amount of cores of an previous installed machine.
Please check it out, because i need the power of more than 2 cores.

[scottgus1]

More cores than necessary slows down a guest, due to extra scheduling oversight needed on the host.

Start the guest from full normal shutdown, not save-state. Run until you see the problem happen, then shut down the guest from within the guest OS if possible. If not possible, close the Virtualbox window for the guest with the Power Off option set.

Please zip and post the guest's vbox.log, using the forum's Upload Attachment tab.

[mpack]

ISTR Michal saying that the Core2 series has a design problem that limits performance.

In any case, 4-4 equals 0. If you leave VirtualBox and the host OS with 0 cores then of course they may perform poorly (remember that the VM is not VirtualBox, VirtualBox is a program running on the host OS).