Simplygon is more than a mesh reducer ,
you can Remesh, create a new texture map
from many textures down to 1 map.
lod,s ect. non destructive does not loose skin weights
on animated characters.
https://www.youtube.com/watch?v=RO6L5zAmSqI
simple reduction
https://www.youtube.com/watch?v=zTlJ58IMwG8
great tool free,
https://github.com/wjakob/instant-meshes
and some tuts for it.
https://www.youtube.com/watch?v=iQcqFfe4cAs
https://www.youtube.com/watch?v=9sV88Z3cXdY