It WILL have a serious impact on the responsiveness of the user interface while posing - in fact, reducing it to unacceptable levels.

yep, confirmed that one.

(slightly expanding the topic):
You know, there is a lot to love about Poser, I've been getting won over these last few months doing animation. I now actually LIKE and appreciate how keyframing / spline wrangling  can be done there.  I just have 3 biggies left in my wishlist for improvements: - export 64 bit RBG (16 x 4 channels)

• animation layers that actually work
• collision detection in animation