How fast does a modern Mac SuperDrive spin a CD or DVD?
According to ISO/IEC INTERNATIONAL STANDARD 10149 (Second edition 1995-07-15), which is the basis for the "1x" speed, the linear velocity at whatever point on the disc is being read needs to be between 1.2 and 1.4 meters per second. That would translate into a different RPMs at different parts of the disc.

A back of the envelope calculation suggests that the fastest a drive in a modern MacBook Pro would spin the disc would be during 24x read at the center of the disc; that would be around 12,000 revolutions per minute.

The full text of the standard is downloadable for free at http://standards.iso.org/ittf/PubliclyAvailableStandards/s025869_ISO_IEC_10149_1995(E).zip