module I18n::Backend::Memoize

def lookup(locale, key, scope = nil, options = EMPTY_HASH)
  flat_key  = I18n::Backend::Flatten.normalize_flat_keys(locale,
    key, scope, options[:separator]).to_sym
  flat_hash = memoized_lookup[locale.to_sym]
  flat_hash.key?(flat_key) ? flat_hash[flat_key] : (flat_hash[flat_key] = super)
end