Hi,
I bought a Targus USB3.0 dock a couple of days ago and I have some slight laggy problems too. Yesterday I also had the problem of fuzzy screens but I fixed that with some Lenovo driver updates.
The laggy issues seems to occur only in the browser (Google Chrome, also in Firefox). When I click the address bar it's taking a second to select the text in it. Also when I click a bookmark folder it takes a second to show me the content of it. This is not unmanagable but nevertheless not that pleasant
My setup:
Lenovo Yoga 13, i7, 8gb ram
24" dual monitor setup (at the moment 1 plugged in directly, 1 through dock but is the same as plugging them both into dock). No wireless devices are connected.