Aside from polygons being the culprit for your slow render times, as RudySchneider has suggested, I can't see anything in your render that's the obvious cause. Slow render times are usually the result of things like numerous complex ART materials, lots of lights, soft shadows, AO etc. and none of these are evident in your render. One other potential cause is massive texture maps but even then I wouldn't expect anything like 35 minutes to render the frame713 image.
I would recommend a process of elimination, replacing complex textured materials with simple materials, removing extra shadow-casting lights etc., until the cause of the slow render is found. Without seeing the project as a whole or knowing your system's capabilities it's hard to say how quickly that frame 'should' have rendered but from what I can see (accepting that there's likely to be a lot I can't see from the render) that frame would have rendered in less than a minute on my system.
