You need to go into the Materials Room and select the material surface that has the problem, using the small document window and/or the drop-down selectors at the top of the materials window.

In the advanced material settings, there will be an Image_Map shader (it may have another name) pointing to the texture file, plugged into the Diffuse colour node on the main shader. The bottom-most setting on the image_map shader is the texture filtering. Change it from Quality to None, then go back to the Pose Room and try rendering. It should be better now.

If there is more that one material surface causing problems, you have to do this for each surface.

Sorry I can't post a screenshot right now, 'cos I'm at work!

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)