Werdj
When exporting from Poser use the .3ds option.
You will get a hierarchy selection option were you can eliminate unneeded meshes, start with ground then work down removing any mesh that is not required like tongue, teeth, body parts that are covered by clothing mesh, etc.
Select yes when prompted to export object groups.
On importing make sure your units are the same as your Poser units (I am set on inches in SU and it works out just fine)
SU will not import textures from Poser, however it will import texture colors that you can select and map your textures to.
Use Poser models sparingly as they are rather heavy in the poly’s and too many of them will slow you down to a trickle, exploding them will take time and every now and again cause bugsplats.