VirtualBox: Is it a bad idea to assign more virtual CPU cores than number of physical CPU cores

VirtualBox: As I have Hyper-Threading capable CPU, I wonder: Is it a bad idea to assign more virtual CPU cores than a number of physical CPU cores as the following warning suggests (simply using all 8 virtual cores of 4 physical core CPU for instance): Transcript: > More virtual CPUs are assigned to the virtual machine than the number of physical CPUs on the host system (4). This is likely to degrade the performance of your virtual machine. Please consider reducing the number of virtual CPUs. Can someone put reasoning to this topic? The CPU in question is Intel Core i7-4700HQ, Ark Intel , CPU Benchmark Supposing, there is no obsolete HW, like HDD (instead of an SSD), and / or Low RAM (16GB here, minimum vm.swappiness , 4GB for this VM), and so on.