Great slideshow from Dmitriy Soroka (Magento Inc.) about Magento performance optimization. There are some nice benchmark results in there, especially interesting for shops with lots of products and/or lots of transactions. I also added some of his tips to my list with 101 ways to speed up your Magento e-commerce website.
Recently I've seen some (often absolute) statements going around, generally in the line of "open source commerce platforms are a terrible idea". Now of course different solutions always have different pros and cons.
A hierarchy of evidence (or levels of evidence) is a heuristic used to rank the relative strength of results obtained from scientific research. I've created a version of this chart/pyramid applied to CRO which you can see below. It contains the options we have as optimizers and tools and methods we often use to gather data.