No one seems to be talking about the operating system “quantum” (also called the “delta” by some).

The (computing) quantum is the minimum allowable number of clock cycles between “context switches”. That is, it is the minimum amount of time the CPU can work on a task without the possibility of being interrupted. This is important as a context switch is relatively resource intensive.

Traditionally the size of the quantum increases with each successive release of an operating system, since the speed of hardware generally increases with time. (althought not so in our current netbook era). Increasing the quantum decreases the time taken for a task to complete as it will be interrupted less often. However it has the side effect of reducing the apparent multitasking ability of the computer. The most noticeable effect of a quantum being set too high is a lack of responsiveness to user input (mouse clicks, etc).

I suspect that the quantum is smaller in Windows 7 than in Vista, and that this combined with smaller cache sizes (and hence less memory usage) accounts for the reports of Windows 7 feeling “snappier” than Vista. The decision to reduce the quantum makes sense in face of the current netbook market, and the never ending story of Windows XP.

Perhaps the quantum is worthy of further investigation (I don’t know if Microsoft would reveal such details). I’d have to think more about how one would compare the quantum of Windows 7 to Vista. It makes sense that benchmarks wouldn’t show the difference, as a benchmark would be the only task running at the time. Perhaps running two different benchmarks at once may yield interesting results.

I just thought the question of the quantum would be a good one for a journalist like yourself to investigate.