I feel like "my favorite interpreted language is slow" is a bit of a cop-out. Granted, it's the first thing that comes to mind when I try to enumerate the things I dislike about working in Ruby, but it's not really an interesting answer.
I might point to simple aesthetic things like JSON-style hashes of symbols looking funny:
example = { a: :b }
=> { a: :b }
example[:a]
=> :b
Or maybe "the way it imports things mean I wind up grepping code / googling docs rather than just looking at the top of the calling file to see the origin of an imported object, and then sometimes I find myself over-stating the namespace for an object just so Ruby won't get it wrong". Compare to python:
from big_library import named_method
I suppose it's a pretty good question and a reasonable proxy for "so you have actually worked in this language for many, many hours, right?"