My guess is that this will not make much difference to the speed.

The limiting factor of most disks in general is not how quickly it reads the data off the disk, but how much time it has to spend moving the read head back and forth and adjusting the speed of the disk and then waiting for the right bit of data to arrive under the read head.

This is why most hard drives specifications quote firstly the "access time", usually in milliseconds, and also the speed in terms of RPM.

On CD and DVD drives, these are very slow.

Also, I believe most CD and DVD drives actually stop the disk after a short period of inactivity (I think only a period of seconds) so the disk needs to be actually spun up to speed repeatedly, and that is probably the slowest thing of all.

However, I would be most happy to be proven wrong.