I do have the same problems detailed by svdl on a rather strong sytem: 2Go of DDR-SDRAM (corsair TwinX LL)working in dual channel, PIV(C) 3Ghz, MB Asus P4C800E-Deluxe, SATA hard drives. I looked at the memory use, and renders may bug with 1.2 or even at 1.7 Go of Ram use... Consequently, it does not come from the amount of RAM. By the way, I noticed no improvement with my second Giga of RAM... If you also consider that so many of us, with very different system, experiment the same kind of problem, this is surely a problem with Poser itself. This means that there is nothing else to do but wait and wait again for a better product from Curious Labs, hoping that their 6th version won't be as "curious" as the 5th!