CD Speed can set the maximum data transfer rate of your CD-ROM drive and limit compact disk rotation speed. These settings will apply to all Windows applications that read data from CD.
When you listen to your favorite music, watch movies or play games, you don't need ultra fast data transfer rate, because most multimedia formats like mpeg, divx, avi, mp3, real media, mp4 are designed to play for a long time and use low data transfer rates. When you lower data transfer rates, it lowers disk rotation speed, lowers noise level and extends your CD-ROM drive lifetime.
CD Speed may help if you have problems with data read, since lower compact disk rotation speeds improve data read reliability. Also you may want to lower the speed if you use low quality CDs that may crash at high rotation speeds and seriously damage your CD-ROM drive.
Give CD Speed a try to see how useful it can be in helping you to manage your optical drives!