When I hooked the laptop up with and Ethernet cable the speed was fine.  It's only slow with a wireless connection.

I booted the laptop up with Ubuntu and used the same wireless adapter and when using Ubuntu the speed was fine.

If there was malware I believe that it would slow the connection with both Ethernet and wireless.  That's been my experience.  I downloaded and installed a different driver that was supposedly for Windows 10 and it didn't work either.