Rake tests running very slow

After running some tests, I'm convinced there has to be something wrong with my setup (windows, rubymine and latest ruby versions). My times right now are:

Finished tests in 14.289817s, 0.0700 tests/s, 0.3499 assertions/s.

1 tests, 5 assertions, 0 failures, 0 errors, 0 skips

Process finished with exit code 0

With 5 VERY easy tests (just checking if validation on empty fields works). The total time for these 5 unit tests is 160 seconds, over 2 minutes.

What could I do to improve this speed?

Here are the tests:

require 'test_helper'

class ItemTest < ActiveSupport::TestCase
  test 'item attributes must not be empty' do
    item = Item.new
    assert item.invalid?
    assert item.errors[:name].any?
    assert item.errors[:description].any?
    assert item.errors[:image_url].any?
    assert item.errors[:rating].any?
  end
end