Dell is recommending the Fresco Logic USB3 Driver version 126.96.36.199, A03
for the Dell XPS13 LS321 on the support site.
It is unclear if Windows Update also supplies this preferred driver. The DocKtor highly recommends that this driver be downloaded and installed to prevent any function or performance issues with any USB3.0 device, especially Targus Universal Docking Stations. Note, there have been four versions of the XPS13 but this applies to the XPS13 LS321.