what mike says has  a degree of truth in that long rendered anims are best handled using output as single frame sequences and then load them to a video editor to create the final output.

 

If all you are doing is a slow turn then start with maybe 30 frames , about 1 second of animation , and if thats too fast make it 60,90 or 120 frames.  Keyframe first frame at 0 and last rame at 360 rotation in y . For a looping anim keyframe the next to last frame and delete the final frame or simply dont render the final frame. That will be seamless when looped.

render a single frame to see how long it will take.  If your render of 1 frame takes 10 minutes a 60 frame animation will take 10 x 60 = 600 minutes or 10 hours.   Render in preview mode is lots faster but you lose some of the textures. 

 

I suggest you try a 320w x 240h render size to get the quickest render, increase the size for the final animation.