While playing on Winamp, your PC slows down because Winamp starts using the cache to save up all your MP3 files being played in your Winamp player. You can reduce the amount of cache you want Winamp to use while saving these files.
* Open up your "system.ini" file, which can be found in Windows directory. Find the line entitled "[vcahe]", and add these lines given below:
MaxFileCahe = X
MinFileCahe = Y
Where X and Y are the largest and smallest sizes, you want to allow for the file cache (in kilobytes) respectively. I suggest putting in a value that is about 25% of your system's RAM. Restart Windows for these effects to take effect.
Winamp 5.3 pro