Bump and normal maps "fake 3D".
They are fake and "simulate 3D" without actually doing anything at all in 3D space.

A displacement map actually displaces its pixels as micro polygons.

In Poser, this displacment map is only calculated at render time.
You see nothing untill after the render has finished.

A 4096 * 4096 displacement map = brings  16,777,216 micro polygons at render time.

And this can be done for each and every material zone.

Yes you can mix sizes.
You can use a 4096x4096 diffuse map, AND a 2048x2048 bump map, AND a 1048x1048 specular map, AND an 512x512 normal map on the same material zone.

YES, Poser can handle 8192x8192 maps.

NO, there is NO limit in texture size. But remember !!!!!!!

All maps have to be loaded and memory consumption will go through the roof......

LOL. Count the number of material zones on V4.

Now "fill" each material zone with a 4096x4096 diffuse texture, a 4096x4096 bump map, a 4096x4096 normal map, a 4096x4096 specular map, a 4096x4096 displacement map, and why not, add a 4096x4096 transparancy map just for fun.

And wonder why Poser slows down.... => Then check memory load.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!