C++ - Fast method for sorting lists

You will be given a working C++ program and asked to do whatever you can to make it run in the fastest, most efficient manner posible. The program is very small only a few short classes but you need to write methods to make them much more efficient. An example of one of the problems is sorting a list, you need to figure out the most efficient way to get the top 10 values in a list of 100,000 values. I expect to pay between $10-15 for this.