I wonder how the benchmarks would be affected by lowering the number of virtual cores assigned to the VMs. At least with VMware products, especially hosted ones, it's often recommended to never set the number of virtual cores equal to or more than the number of physical cores (ie. not counting hyper-threading logical cores). Some (many?) workloads supposedly get better performance by doing this.
No announcement yet.
VirtualBox Is Still Running Slower Than QEMU-KVM