Common issues with the VIT part of iNZightVIT.
On macOS, the default graphics device is very slow at drawing, which is particularly a problem in the VIT module when fast animations are necessary. This means VIT has to wait for each frame to be processed before it can move onto the next, which results in a very slow, laggy animation.
To get around this, a much faster graphics device should be used, and in most cases this will be installed along with iNZightVIT. This packaged is called Acinonyx. In some cases, however, it may not have been downloaded and therefore unavailable for VIT to use.
If that gives you an error message, you will need to try installing it by pasting the following command into the R Console and pressing Enter:
install.packages("Acinonyx", lib = "/Applications/iNZightVIT/.library", repos = "http://rforge.net)
If you're still unable to get VIT running to your liking, please email us with screenshots of VIT with the graphics window open. Include as much detail as possible, including macOS version and R version, and any results from attempting the above instructions.