I've already solved my problem.
I don't know how to explain it but i've noticed that the stall spots were exactly over some kind of white odd wireframes produced along the block representing the floor, where other blocks intersect it's surface.
I lifted those blocks like 1 quant up, enough to stop the intersection.
Result: odd jaggie wireframe gone and the entity stalls no more.

As for the animated wall textures...
I've reinstalled GS with the downloaded new version, under my bought license (commercial), but the textures don't animate. Only in the thumbnail.