When running several applications/processes simultaneously then a coordinator/scheduler is needed to make sure that all applications get a fair quantum/slice of the CPU time. The coordinator can be configured in how it gives CPU quantums to the different applications running.
Foreground vs. Background: Foreground boost means that the application currently having focus will get more quantums than other applications, thus it will not be disturbed that much by background processes. Background means that all applications gets equal amount of CPU quantums.
Short vs. Long (Win2k+): Short quantums means that applications can hold the CPU for a short time, thus giving smooth multitasking. Long quantums means that applications can hold the CPU for longer time, thus spending less time on process switching.
Variable vs. Fixed (Win2k+): Variable quantums means that the foreground application can hold the CPU for a longer time. Fixed quantums means that the CPU time within a quantum is the same for all applications (Though some applications can get more quantums than others).
This setting can be configured at "Control Panel" -> "Systerm Properties" -> Advanced-tab -> "Performance Options...".
In this setting can be configured at "Control Panel" -> "Systerm Properties" -> Advanced-tab -> "Performance Options...".
The above setting reflects this DWORD value in the registry:
[HKEY_LOCAL_MACHINE \System \CurrentControlSet \Control \PriorityControl]
Win32PrioritySeparation = 26
For the there are the following values:
0 - Equal priority for all applications
1 - Medium priority to foreground application
2 - High priority to foreground application
Adjust for best performance of Background Services Win32PrioritySeparation to 18 (decimal 24) for Background Services.
Adjust for best performance of Programs, you will find that it sets Win32PrioritySeparation to 26(decimal 38) for Programs.
UPDATE: Note EZ Game Booster does *not* use foreground priority boosting, it instead relies on changes the CPU scheduler to give the foreground application longer time slices. This is an entirely different technology!