You might assume that it would have no effect, but an SSD reads data in a block. If the size of each fragment is smaller than a block then it will definitely slow it down.
But it depends on how large a block is on the SSD.
I think SSDs call them pages. Some brief googling seems to indicate that 16KB is a common page size, so if the cluster size is also 16KB it's probably not too bad.
But it depends on how large a block is on the SSD.