I asked Google AI, and it gave me the following answers:

time echo "scale=7000; 4*a(1)" | bc -l
time dd if=/dev/zero bs=1M count=4096 2>/dev/null | sha256sum

Both gave almost identical results for both QEMU and VirtualBox. Granted that they are pure "cpu", but I just want to compare. Man, AI is good!

Kernel compile is more comprehensive (cpu, ram, disk), but it takes too long, and lot of things will skew the result.

On 2026-05-25 14:30, Lennart Sorensen wrote:

On Mon, May 25, 2026 at 12:53:10PM -0400, William Park via Talk wrote:

I'm running Kubuntu 26.04 inside QEMU and VirtualBox.  Now, QEMU (with KVM
enabled, --enable-kvm) is supposedly be faster, but strangely it seems
slower to me.  I am compiling kernel now, but that takes 2 hours on 2 cpu,
which mean I have to wait 4 hours to find out.

Is there a quick way to test cpu/ram/disk, by "quick", I mean 5min max?

As for performance, it also depends how much ram you gave the VM, the
disk interface type, the backing store used for the disk, how many cpu
cores, etc.

Certainly I have seen many places claim qemu tends to win by 15 to 30%
over virtualbox.

https://www.youtube.com/watch?v=k0uaszySbfc for example