Is before_action/filter in application_controller.rb a bad practice? - Rails 4

Consider the following

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  before_filter :maintenance_mode

private

def maintenance_mode
      @settings = Setting.first
      if @settings.maintenance
        if logged_in?
          if !current_user.admin?
            redirect_to maintenance_url
          end
        else
          redirect_to maintenance_url
        end
      end

end

is there a performance issue or bad practice in general to use before_actions globally? So i created a maintenance mode, where if in the database there is a true value on the maintenance attribute(which will be checked on each request i assume), and its likely not the best way, so is there a workaround in that?

I can imagine of a cron job/rake tast checking every minute in a background process but what i really want to know is before_action a bad thing in general?