A computer system for providing virtualization services, the computer system comprising one or more central processing units, CPUs, one or more additional CPUs, and a memory storing computer-readable program code portions that, in response to execution by the one or more CPUs and one or more additional CPUs, cause the computer system to: identify one or more computer programs executable as a plurality of tasks, the identification including identifying, from the plurality of tasks, one or more foreground tasks and one or more background tasks, other than the foreground tasks, that can be parallelized with the one or more foreground tasks; and execute the one or more computer programs by one or more virtual CPUs in a virtual machine defined to provide a virtualization platform for virtualization of a target hardware platform, the execution including being caused to: execute the identified one or more foreground tasks by the one or more virtual CPUs in the virtual machine executed on the one or more CPUs of the computer system; and execute the identified one or more background tasks on the one or more additional CPUs of the computer system, such that the identified one or more background tasks are executed by the one or more additional CPUs of the computer system at least partially in parallel with execution of the one or more foreground tasks by the one or more virtual CPUs in the virtual machine, wherein the target hardware platform includes a number of CPUs for execution of the plurality of tasks, the number being no greater than the number of CPUs of the computer system on which the one or more foreground tasks are executed, and wherein the plurality of tasks are scheduled for execution at respective points in an apparent time tracked by an apparent-time reference, and wherein, during execution of the one or more foreground tasks, the computer system is further caused to at least: detect a current point in apparent time at which all foreground tasks of the plurality of tasks have been executed, or at which the one or more virtual CPUs are idle; and in response thereto, advance the apparent time from the current point to a subsequent point with a frequency greater than that with which the apparent time is tracked by the apparent-time reference. identify one or more computer programs executable as a plurality of tasks, the identification including identifying, from the plurality of tasks, one or more foreground tasks and one or more background tasks, other than the foreground tasks, that can be parallelized with the one or more foreground tasks; and execute the one or more computer programs by one or more virtual CPUs in a virtual machine defined to provide a virtualization platform for virtualization of a target hardware platform, the execution including being caused to: execute the identified one or more foreground tasks by the one or more virtual CPUs in the virtual machine executed on the one or more CPUs of the computer system; and execute the identified one or more background tasks on the one or more additional CPUs of the computer system, such that the identified one or more background tasks are executed by the one or more additional CPUs of the computer system at least partially in parallel with execution of the one or more foreground tasks by the one or more virtual CPUs in the virtual machine, execute the identified one or more foreground tasks by the one or more virtual CPUs in the virtual machine executed on the one or more CPUs of the computer system; and execute the identified one or more background tasks on the one or more additional CPUs of the computer system, such that the identified one or more background tasks are executed by the one or more additional CPUs of the computer system at least partially in parallel with execution of the one or more foreground tasks by the one or more virtual CPUs in the virtual machine, wherein the target hardware platform includes a number of CPUs for execution of the plurality of tasks, the number being no greater than the number of CPUs of the computer system on which the one or more foreground tasks are executed, and wherein the plurality of tasks are scheduled for execution at respective points in an apparent time tracked by an apparent-time reference, and wherein, during execution of the one or more foreground tasks, the computer system is further caused to at least: detect a current point in apparent time at which all foreground tasks of the plurality of tasks have been executed, or at which the one or more virtual CPUs are idle; and in response thereto, advance the apparent time from the current point to a subsequent point with a frequency greater than that with which the apparent time is tracked by the apparent-time reference. detect a current point in apparent time at which all foreground tasks of the plurality of tasks have been executed, or at which the one or more virtual CPUs are idle; and in response thereto, advance the apparent time from the current point to a subsequent point with a frequency greater than that with which the apparent time is tracked by the apparent-time reference.