Oh yeah... a hub can choke the transfer especially if it isn't USB3 all the way. Best bet is to find and use your USB3 ports for your USB3 device. There is backwards compatibility but it brings you back down to USB 2.0 transfer rates (and sometimes less from what some people say). And sometimes hubs are just crap even if they say they are the right connection.
For streaming libraries you definitely want to have the drive hooked directly up to the motherboard's USB ports (not the case ports or through a hub or even an extension cable). Also I'm not sure if this affects external drives but a general rule for most audio stuff VIA USB is choose a port and stick with it. That way windows isn't scrambling around trying to find stuff.
Basically the try to choose the most direct path for data to flow to the system for anything that requires high speed data transfers.
I may be way off as I'm not an expert but it's just general stuff I've seen discussed. Hope you get it all working as intended.
Cheers.