In general file IO is orders of magnitude slower than in-memory operations, so if you are receiving the volume data in the same program that is displaying it, removing the file IO will help a lot.
You could test potential volume performance in ParaView - I’m not quite sure how you can do it, but I think if you create a Wavelet source of the same resolution as the volumes you are interested in, and then look at the Animation options - if you change one of the options on the Wavelet using animation, you should be able to get ParaView to have to regenerate the source each frame, which simulates what you are trying to do - and you can see how fast ParaView can do it, and even test larger resolutions easily, if that is of interest.
HTH, Aron