Corona materials library is very useful, but it's quite huge and takes forever to load and render previews. Have you ever considered splitting materials into categories like Hair, Plastics or Wood into separated 3ds max libraries? I'm NOT talking about Corona Material Library but built-in 3ds max Slate Material Editor materials.
That way users would only load materials that they really need. For example, me as product designer, I hardly use roof tiles materials or wall materials or wood siding boards. This would also speed up loading Slate Material Editor and rendering materials previews.