If you have a benchmark comparing C with a functional language then it is almost certainly an extremely simple program. Arguably so simple that it is of little practical relevance today.
A lot of simple tasks are highly relevant. For example, in numerical simulation, you probably want a fast matrix-vector multiply. Conceptually this is extremely simple, and it's easy to benchmark. Examples of practical relevance: climate modeling, simulating combustion in engines, and optimizing control surfaces on airplanes.
"Sort" is simple. Does that make it irrelevant?
How about finding the standard deviation of a bunch of numbers?