There are a lot of functions that are related to numerical computation of integrals, numerical solutions of algebraic/differential equations, etc. In such functions there a lot of different methods (for instance, NIntegrate and NDSolve contain many strategies/methods).
Question: Can I safely assume that these built-in functions and methods (to be more specific, consider NIntegrate and NDsolve , and their methods) are completely optimized and tuned? So, any attempt to realize this functions by hand is slower than existing realization?
To be more specific, let me consider the numerical solution of a differential equation with 4-th order Runge-Kutta method. In principle, I can realize by hand such scheme and perform the explicit performance comparison between my code and NDsolve with with Method->"ExplicitRungeKutta" but the question is more general.
Can anyone provide the references/examples where this question is discussed? My interest is mostly about NIntegrate and NDSolve, then about RandomFunction.