Is there a way to save the visual previews so that it does not have to reload when switching between projects? It is very time consuming having the previews load again and again. 

Thank you.

The visual previews are being saved. They will not be created again, when you load a sequence, that already has visual previews generated (only if the metadata of the sequence is changed externally).
But of course that cached previews have to be loaded. But this is much faster then the creation.
You will see that the green bar appear below the previews when they get loaded from cache. If they get created, the bar will be yellow first and then turn green.