Slow SD on Inspiron 13 7000 (7368)

The SD is a new SanDisk 128GB rated at 95MBS read and write, model no SDSDXPA-128G-G46.

Using Crystal Mark, I get 30 MBS R/W sequential on my Dell XPS8700 desktop under Win7HP.

On the 7368 under Win10, I get only 15 MBS R/W.

OTOH the USB 3.0 port on the 7368 is around 40% faster than the XPS when using a thumb drive rated at 260/240.

Why these significant differences?

Is there any way to sped up the SD R/W on the 7368? Maybe an aftermarket driver? Or does Crystal Mark bypass the installed driver and gives me the max possible hardware speed?

Ken C