That's kind of missing the point. In statistics, there exists something called confounding variables. Confounding variables are factors that affect your outcome, but are hidden, or are outside your control. As your example becomes more complex the opportunity for confounding to impact your result goes up significantly.
I believe the multi-query database access test is actually a good example of a "complex enough" test, but not too susceptible to confounding. In this test, we see that Rails isn't so far behind.
Basing your choice of framework on speed alone is a pretty bad idea. When you select a framework, you need to optimize for success, and the factors that determine the success of a project are often less related to the speed of a framework and more related to the availability of talent and good tools.
That's not to say you should ignore speed entirely, but that you have to weight your factors. There is a tendency to believe that you will need rofflescale when you really won't. Keep that in mind when you're weighting your factors.