Does anyone know why simplemining OS dag fix does not give as high hasrate as windows?

For example,
I modded the bios, then overclock,
with the new DAG driver fix on WINDOWS 10, I get 31 Mh/s on my RX 580 8gb.
with the new DAG driver fix on Simplemining OS, I get 28Mh/s on my RX 580 8gb.

why is this the case?
does anyone know?