spec.rb

# Note the differences between this and https://gist.github.com/2938822 are that
# we're making 10k groups with 1 example each vs 1 group w/ 10k examples, and the
# rspec example uses "should eq" instead of "should =="

if $0 =~ /rspec$/
  10_000.times do |i|
    describe "loltest #{i}" do
      it "does #{i}" do
        i.should eq i
      end
    end
  end
else
  require 'minitest/autorun'

  10_000.times do |i|
    describe "loltest #{i}" do
      it "does #{i}" do
        i.must_equal i
      end
    end
  end
end

__END__
On my machine:

$ time ruby spec.rb
Run options: --seed 29086

# Running tests:

[dots omitted]

Finished tests in 2.930095s, 3412.8586 tests/s, 3412.8586 assertions/s.

10000 tests, 10000 assertions, 0 failures, 0 errors, 0 skips

real	0m5.038s
user	0m4.931s
sys	0m0.108s

$ time rspec spec.rb

[dots omitted]

Finished in 2.35 seconds
10000 examples, 0 failures

Randomized with seed 59780


real	0m4.358s
user	0m4.153s
sys	0m0.204s