Since I installaled P6 (on the download date) I havn't used P5 at all. P6 is faster and have some nice new stuff for rendering, the mat room is better, there is a lot of improvement in P6. I would suggest you get P6 if you use Poser a lot or want to in the future. I too had problems with P6 in the beginning, but now it runs smoother and faster than P5 did.