Using USB splitter with USB-C Macbook pro 2016
You won't get faster than USB 3.0 speed on the link to the Mac or any of the hub links. (You'd need a thunderbolt 3 hub for that.)


USB 3.0 theoretical speed is 5 Gbit/s
USB 3.1 theoretical speed is 10 Gbit/s


Theoretically - when you have a hub, there is overhead and losses and those depend on the quality of the chipset in the hub.

In practice - what is going to be providing or consuming data at even 3 Gb/s - not much. Get the hub you like for the support and price and warranty and when you have an actual performance issue - you can profile it and get a second hub or offload the one device to another port.