RSpec speed-up (24.6%) by tweaking ruby garbage collection

Today I learned that Ruby garbage collection can be of huge importance to performance. More precisely, if Ruby does a lot of garbage collection it may slow down your code. Running garbage collection only every 10 or 20 seconds when running specs may increase performance dramatically. At this time specs for Ariejan.net take an average of 25.29s to run. This is not bad, but in my opinion faster specs are better.