One of the more compelling reasons to chose C/C++ for a project is good performance. Good performance is not automatic, however and requires a combination of experience, understanding, good design and hard work.
Performance also tends to put stress on the rest of your code in terms of readability, reliability, adaptability, and maintainability. Try to avoid the temptation to put the importance of performance above all other factors.
Small speeches aside, the Str class provide a number of facilities for
tweaking performance. This chapter talks about the potential bottlenecks of the
Str class and how to avoid them.