well after looking at the file i can tell you that my computer took 23 minutes to render a shot without touching anything, but then after converting all the lights in the scene to spotlights it reduced the rendering time to 13 minutes, which is close to half... so i would recommend looking into that and playing with your cone angle (around 179 should do it... i rendered with 160 and the top was a little dark) to come up with a similar feel.