FastDL or Workshop for server ?

Best bet is to place ALL of the Lua onto your server, and take the materials/models/sounds and what not into content packs via the workshop. FastDL is, yes - fast. However, i prefer WorkshopDL so players can pre-subscribe to the content and have open access to it. It's tedious extracting everything and reuploading it into content packs but it makes the collection for one, 10x smaller (in looks) and your lua will all be serverside so you can manipulate it at any time you need.

I've personally only used FastDL for a minuscule amount of files and it honestly wasn't worth it.