.where (or scopes) on associations triggers queries even if the association has already been loaded. @justinweiss wrote a great article about converting scopes to associations to fix this common N+1 cause: https://www.justinweiss.com/articles/how-to-preload-rails-scopes/ … I tend to just use Enumerable (`select`) if poss.
Depending on the number of filtered records, the cost of sending them over the wire, deserializing into Ruby objects, and filtering may be non trivial
