Is there a known limitiation of files (cr2's, pp2's) OR filesizes, that can be loaded on P5?
I made a max. test with 12 different Figures (different meshes, average 7 MB the mesh file 10 MB the cr2 file, including each 10 props).
I could load them, the preview was OK, it took time though, but it could not be rendered (I use the P4 render engine), the prog crashed (it froze in).
A test with half of the figures went fine.

So...
Is it known that Poser can only cope with a certain number of files loaded or is it simply dependent on the PC Hardware used (like RAM, CPU). I use Athlon 1,2 with 768 MB of SDRAM with Win2k.
Would more RAM (which would be impossible for my current Motherboard btw ;o)...) or a faster CPU provide for better results?

More RAM sounds like the solution. I don't know of any technical limit in Poser itself, but I would believe it's the machine that sets the limits before the software will reach it. I have had scenes in Poser 5 that were well above 200 Mb and using a fair amount of hi-res textures. My system specs: 2.2 GHz P4 and 1 Gb RAM running on Win XP. The PC was complaining about having to extend the swap file size during rendering in FireFly production mode, but it worked... This leads me to believe that your PC is the limit here, not Poser itself.

I have been having great trouble rendering a scene using Vicki3 as a base with hi-res texture maps and displacement maps - the render will often get part way through before Poser 5 crashes (this is using the firefly renderer) I have a P4 2.8GHz machine with 1GB Ram and upto now have had no problems with Poser.

I have a Celeron 700 adn 256 MBs of RAM. My M2 .cr2 is an easy 90MBs, and I know off hand my P4NW has around 1500MTs. These both load, save, and render fine in P4 and P5. It just takes a minute, almost exactly. I noticed this yesturday. I have my screen saver set to 1min, and each time I loaded, or saved, my HD light would stop going on just as my screen saver cam on. My renders on this 1600x1200 screen are about that too!

There is a software limit-- at one point Jaager was discussing this with Kupa. I think, from has been mentioned since on Poser Pros that Vicki 3 loaded reaches it. Jaager would know more. Vicki3's head is 120MB at least and, I thought-- with my limited memory that 300MB [that might be per figure] was Poser's limit. You're getting this third hand and not terribly reliable but my work with Vicki 3 in P5 bore it out. Emily