If you don't need a poster sized image why render one? I usually render my images at 4 x 6" 300 ppi and have never had renders that take that long. The biggest I'd probably go is 8.5 x 11" because that is the limit of the size my printer will print. If you don't need a super big image, why not render a smaller one and keep your Vue 3D file so that a larger pic can be made if needed in the future. Just think of all the hard disk space you'll save too.