I've seen some really good animations created in earlier versions of Poser.  From what I've read Monty Oum did his animations using Poser for his Dead fantasy series. http://montyoum.net/videos/deadfantasy01 .  I've also seen some Poser Hair animations that are excellent too.

As for the issues with the slow responsiveness with your UI, it sounds like it may be an issue with your computer's processing and memory capabilities.