hash-bench.rb

def benchmark
    times = 86400
    Benchmark.bm do |b|
      b.report("object") do
        hash = {}
        times.times { hash[Date.today] ||= {} }
        puts hash.size
      end
      b.report("string") do
        hash = {}
        times.times { hash[Date.today.to_s] ||= {} }
        puts hash.size
      end
    end
end

      user     system      total        real
object 1
  2.730000   0.060000   2.790000 (  2.964457)
string 1
  6.770000   0.060000   6.830000 (  7.292075)