A vCPU (virtual CPU) is the compute unit assigned to a virtual machine. The hypervisor maps it onto physical CPU cores or their threads (Hyperthreading/SMT) — with many providers several vCPUs share a single physical core. How much real performance a vCPU delivers therefore depends heavily on whether the provider practises overprovisioning : if more vCPUs are sold than cores exist, customers compete for CPU time and performance fluctuates. Bthorio's cloud servers use no overprovisioning — every vCPU is permanently reserved for you. That keeps performance predictable no matter how busy the host is.