This opensource libraries that you mention (and most in general) are focused in generic constructs of methods for the solution of partial differential equations (PDEs).
PyFR - flux reconstruction.
OpenFOAM - Finite Volume.
The list is actually extensive, there are libraries with focus in Finite Element, Finite Difference, Boundary Element, Smoothed Particle hydrodynamics and so on.
The difference here is that this is a solver, not a library. So it is focused on a specific set of PDEs, by doing so you can apply optimizations that are specific to this PDEs and the space representation that it uses, this optimizations are not general to the underlying method of solution (which can actually be a combination of methods), so it will be extremely hard for this generic libraries to compete in performance with a focused solver.