Slightly surprisingly small amount of performance difference for these three methods of getting things done...

module_class_instance_method_comparison.rb

require 'redis'
require 'benchmark'

module ModuleMethods

  def self.record_metric(name)
    $REDIS.lpush(translate_name(name), Time.now.to_f)
  end

  def self.translate_name(queue)
    queue.to_s.start_with?('adsentry:') ? queue : "adsentry:#{queue}"
  end

end

class ClassMethods

  def self.record_metric(name)
    $REDIS.lpush(translate_name(name), Time.now.to_f)
  end

  def self.translate_name(queue)
    queue.to_s.start_with?('adsentry:') ? queue : "adsentry:#{queue}"
  end

end

class InstanceMethods

  def initialize(name)
    translate_name(name)
  end

  def record_metric
    $REDIS.lpush(queue_name, Time.now.to_f)
  end

  private
  attr_reader :queue_name

  def translate_name(queue)
    @queue_name = queue.to_s.start_with?('adsentry:') ? queue : "adsentry:#{queue}"
  end
end


$REDIS = Redis.new

Benchmark.bmbm do |x|
  x.report("module") { 100000.times { ModuleMethods.record_metric(:module) }}
  x.report("class")  { 100000.times { ClassMethods.record_metric(:class)  }}
  x.report("instance")  { 100000.times { InstanceMethods.new(:instance).record_metric  }}
end

# Rehearsal --------------------------------------------
# module     5.440000   2.340000   7.780000 (  9.761189)
# class      5.490000   2.340000   7.830000 (  9.808614)
# instance   5.550000   2.350000   7.900000 (  9.888947)
# ---------------------------------- total: 23.510000sec

#                user     system      total        real
# module     5.470000   2.330000   7.800000 (  9.771679)
# class      5.470000   2.340000   7.810000 (  9.786765)
# instance   5.510000   2.340000   7.850000 (  9.815554)