Well, MathLab is really powerful because it is made for mathematicians and it is hiding all the fine things that make numeric methods hard to implement. But in the same time as it is general, it might get slow or resource-consuming on special or concrete tasks. Yes, in general porting a problem solution to a language like C would make it much-much faster. But doing it would be in general really hard - even for experienced C programmers without experience in mathematical problem solving. Java or C# solutions would be somewhat in the middle of the scale - but you could find several ready-made mathematical libraries you could use.
I said in general. Because it depends much on the concrete problem.
Let's say, if you are doing some smaller task, but many times, you could get better results in a shorter timespan; but if you try to solve a one-time problem that is complicated... well... than you will have to face several challenges.
To get some ideas about numerical methods, have a deeper look in this great book:
http://www2.units.it/ipl/students_area/imm2/files/Numerical_Recipes.pdf[
^]. Well, most of this is what you don't have to deal with when using MathLab.