Of you mean scaling a figure down, and then zooming in closer to get the same render view then no, it wont save resource. Scaling the textures may give you a slight quality hit, a big quality hit or no noticable change depending on a bunch of factors involving the size, number of pixels in the render, and number of pixels in the texture.

I have not noticed a quality difference between using 3,000 x 3,000 image maps and 2,000 x 2,000 although its half the size.