Hey People!
I also treated myself with a Targus DisplayLink dock. I experienced the same lags with the wireless keyboard and mouse. It seems that I found the fix for my issues.
I have an Asus Zenbook UX31E ultrabook. I also upgraded to Win8.1 Pro and I didn't pay much attention for checking hw installation as everything worked at the first boot.
However my ultrabook is equipped with a Fresco Logic USB3 controller. Windows installed a Microsoft-made driver for it. As I changed the driver to the Fresco make, all my problems disappeared!
Check your hw configs and see whether the right usb controller driver is installed!
Fresco LoGic driver:
http://www.frescologic.com/file_dl.p...0zLjUuMTAwLjA=
Good luck!