Your input looks suspiciously like a hexadecimal number. Are you sure you need to be passing around strings instead of numbers?
If you really do need to work with strings, why not keep it as strings instead of converting down to bytes?
You can get a little more performance (>10x?) if you don't use build array in a loop and avoid regex
Just to break the monotony, here's yet another possibility.... 😄

(of course tweaks might be needed if the number of input characters is not even or if the last space is unwanted, for example)