Attached Link: Why doesn't hair render properly in Firefly?

Don't use texture filtering.  That will make the image blurry, and cause seam problems with many textures. 

The link above has a lot of great info on getting the best from Firefly.  I love Firefly myself, but it does have more of a learning curve than the P4 renderer.

For a final render, I usually set the shading rate to 0.05 or lower.  Not 0.1.   0.01 is more like it. 

Also, shading rate must be set for each item in the scene, not just in the final render settings.  (This is actually a good thing.  You can set different shading rates for different objects/parts, to save render time.  Also, it lets you do test renders at a higher shading rate, no matter what each object is set to.  When you're ready to do your final render, you can lower it in render settings, without having to tweak each object in the scene.)