Didn't make sense to me either. Now I realized it optimizes static content: css, javascrips and images on the firs run, then it serves optimized version until y

Didn't make sense to me either. Now I realized it optimizes static content: css, javascrips and images on the firs run, then it serves optimized version until you update them. There is some latency to fetching dynamic content and that's the reason optimized sites are slower on this test.