Does the specific size of matrices affect the performance of matrix operations?
While you can only be 100% certain when you ask the authors, most authors use this simply because you have to choose one value. The specific value doesn't matter too much, only the order of magnitude. Taking a power of 2 seems to be a natural choice.

You can also take a setup which uses a power of two and reduce the number by one. The computation time should be roughly equal, probably be a bit lower. If it is noticeably higher, there might be a performance benefit of using the choice of the author.

See also


Datascience.SE: Why the number of neurons or convolutions chosen equal powers of two?
Quora: Should I use powers of 2 when choosing the size of a batch size when training my Neural Network?