audio interface motu 8 pre usb2
Your MacBookPro has USB3 ports and there are certain instances where those have been found to have problems with USB2 devices even though those are supposed to be compatible. iLok2 dongles don't like USB3 ports and the usual remedy is to run a powered USB2 hub between the iLok and the computer.
Have you installed the latest drivers from MOTU?
The V Pianos are modeled and they will suck up cpu horsepower like crazy. Have you optimized your computer for audio work? Try running VPianos at a lower sample rate of 44.1 KHz and see what happens. That 128 figure is NOT sample rate.