Vray-rt, afaik, isn’t much faster than vray cpu. It’s just different.
For the render time it depends on the scene complexity. If you need 3 hours to have a noise-free image… then a 2 mins animation @ 24 fps is 2880 frames that you need to render. Do you see why you need a render farm?
Heck, even if you could render each frame in 5 mins, it’s still 240h of rendering.
With real-time you can record a video in 60 fps instantly. The tradeoff is realism.