Thanks for the MilkShape BVH importer tip, bradford6. The free version is still out there at http://www.fileplanet.com/index.asp?section=1429&noloop=1&file=62995 - I got it a couple of days ago and have only tested it out briefly, but it looks like it does the job.
Poser does include some "low-poly" models (low relative to its default, high-poly ones). I tested some in Blitz a while back and found the speeds acceptable when repeatedly rescaling eight of them on-screen at once:
Poser3 (28,820 triangles each) = 11 FPS
Poser2 (17,538 tri's) = 16 FPS
P4Lo (4,410 tri's) = 69 FPS
P2Lo (4,170 tri's) = 74 FPS
Poser1 (3,436 tri's) = 85 FPS
Poser does include some "low-poly" models (low relative to its default, high-poly ones). I tested some in Blitz a while back and found the speeds acceptable when repeatedly rescaling eight of them on-screen at once:
Poser3 (28,820 triangles each) = 11 FPS
Poser2 (17,538 tri's) = 16 FPS
P4Lo (4,410 tri's) = 69 FPS
P2Lo (4,170 tri's) = 74 FPS
Poser1 (3,436 tri's) = 85 FPS