FC++ uses a number of optimizations to improve the performance of its more "dynamic" features, like indirect functoids and lists. Sections 9 and 10 of [McN&Sma to appear] quantify the library's performance and discuss a number of the optimizations we have implemented.

For the most part, using FC++ means using direct functoids, which are templates which get instantiated (and possibily inlined) at compile-time; this use of FC++ implies no extra overhead.

FC++ is a large library, and #include-ing it is bound to slow down your compile-time a little. The lambda and monad facilities utilize expression templates, and expressions templates tend to slow down compile-times a lot.