Windows especially Windows 95/98 does not give allocated memory back to the user. So memory decreases till nothing is left. If more memory is needed then the operating system frees memory. The disadvantage is that if you start an application, most times there is no more memory left at the beginning. Then Windows starts his deallocation algorithm taking the time needed to start the application. With this menu you could choose a strategy to free the memory before starting the application at a time windows has to do nothing else.
Good values are for 64 M Byte to free 16 M Byte if there are only 2 M Byte left after a time of 10 sec. It is not useful to free more than half of memory.
You can do it periodically every e.g. 30 minutes as well.
Initially this option is switched off because CPUCooL could not detect whether there is a CD-ROM burner is working or not. If a CD ROM burner is working in 486 systems you should switch off this option because it might delay the data output from the CPU a little bit on slow systems.
Before starting a game it is a good thing to tell CPUCooL with the right mouse button in the tray menu that a game is going to start. Then CPUCooL frees the memory, suspends cooling, and cancels all its own periodical tasks. So you will get a higher frame rate than ever.