< 0.5s load time (showing off)

[pmeenan]

Pagetest, PageSpeed and YSlow all have different core rules and weights for the grading. With Pagetest I was pushing to focus on just the key big wins that will really improve performance and that are just about universally applicable.

In this case, pagetest only recommends combining js and css that are loaded before start-render. Otherwise you might end up in a situation where you are pulling code from the bottom of your page and merging it in with blocking code in the head and actually doing more harm.

The CDN detection in Pagetest is also significantly better out-of-the-box. If you configure YSlow to know about your CDN you should see that score improve.