I've never used the Levenber-Marquardt function and can't speak to the speed of the algorithm, but everything in LabVIEW is compiled. The description of the Initial Guess Coefficien input also says "Using this function successfully depends on how close your initial guess coefficients are to the solution. Therefore, it is always worth taking the time and effort to obtain good initial guess coefficients to the solution from any available resources before using the function."
