When using paper_trail and devise, new user versions are saved on each request. The following prevents saving new user versions when devise trackable columns (sign_in_count, current_sign_in_at, last_sign_in_at, current_sign_in_ip, last_sign_in_ip) are updated.

user.rb

class User < ActiveRecord::Base
  devise :trackable
  has_paper_trail
  
  def update_tracked_fields!(request)
    without_versioning { super(request) }
  end
end

Tested on Rails 4.0.1, Devise 3.0.3, PaperTrail 3.0.0.beta1.