When recording at full speed, you are more likely to introduce error (this could depend also on your media / recorder and so on ...)
On a CD Audio, an audio block is 2352 bytes.
On a Data CD, there is typically 2048 bytes of data available per block, the remaining (2352-2048 ) being used for error control / checksums.
Audio CD don't have that extra layer of error control, so if this a record that you care, I would not recommand burning too fast.