What are the performance issues associated with generating 100's of dynamic methods in Ruby?

I've been interested in using the Ruby Preferences Gem and noticed that it generates a bunch of helper methods for each preference you set.

For instance:

class User < ActiveRecord::Base
  preference :hot_salsa
end

...generates something like:

user.prefers_hot_salsa?         # => false
user.prefers_hot_salsa          # => false

If there are 100's of preferences like this, how does this impact the application? I assume it's not really a big deal but I'm just wondering, theoretically.