are u using ''ambient occlusion''? for exampe, i don't use AO, i simply turn it off and then add a bunch of lamps in the scene, and on my E6850 - 3.0ghz and 4 gigs of ram it takes me a few seconds to make a 1600X1200 render i have tried to make 4084x3072 render and that one took about 5minutes or something like that.
here's a picture: http://imajr.com/ambient-occlusion-1163148
just disable the AO and import some lamps, it should do the trick
here's a picture: http://imajr.com/ambient-occlusion-1163148
just disable the AO and import some lamps, it should do the trick