Abstract: A system, method and computer program product, including a primary operating system (OS) having access to at least some hardware resources of the computer system. A Hypervisor controls a plurality of virtualization spaces and at least some of the remaining hardware resources. Each virtualization space maintains data of a corresponding instance of a Virtual Machine with a guest operating system running inside the Virtual Machine. Each Virtual Machine is associated with at least one virtual processor. A hyperswitch controlled by the Hypervisor starts and stops execution of the Virtual Machines. A scheduler dedicates a quantum of running time to each virtual processor. When the quantum is given to the Virtual Machine, the Hypervisor forces the hyperswitch to activate the Virtual Machine on its virtual processor.