I see in the last build of VP 17 a big difference between the preview velocity of that nested veg and playing the project itself. Not so encouraging to use nested vegs and when more than one nested vegs is used in a project the program freezes a lot. Look for the first issue
It is on and with it is turned off in options/preferences/video also the playback in the project itself is not anymore steady on 50fps. In the nested veg it gives no differences, never 50fps.