Under many operating systems like Windows NT and Linux the CPU issues an HALT operation when there is nothing to do. That enables a CPU build in functionality that reduces the power consumption. That keeps the CPU cool and saves money. If you overclock the CPU it is advisable to use such a program as the CPU gets hotter as specified.
Unfortunately there is no HALT operation under Windows 95 / 98. The CPU permanently checks whether there is something to do or not. Many other programs like CPUCooL put in a task at low priority which issues a HALT instruction. But it costs time to make the new program run.You can see these programs work with the Microsoft WinTop Monitor. It shows 100 % activity although there is nothing to be done by the CPU.
CPUCooL has an other technique to solve this problem. Look at WinTop and you see the difference. Wintop shows the normal idle time as before. CPUCooL integrates the HALT operation directly into Windows 95 / 98.
The other advantage is that you can only switch off this cooling function by CPUCooL. There is no other way. Even if CPUCooL is terminated the cooling functionality is still alive!