Linux KVM Continues Offering Much Better Out-Of-The-Box Performance Than VirtualBox
Even with the fixed-size VBOX disk and all tests being off the same Samsung 970 EVO NVMe SSD, the out-of-the-box VirtualBox storage performance is much slower than KVM... Of course, there is the possibility to setup alternative storage mediums but at least for the default experience, KVM was much faster.
For CPU benchmarks with all three test configurations having access to 16 CPU cores, the VirtualBox performance tended to be a great deal slower than KVM. As for the KVM performance, it varies based upon the particular benchmark how close the performance was to the bare metal configuration.
In many tests, the KVM overhead was quite small.