Zero Cost Abstractions

Zero Cost Abstractions means adding higher-level programming concepts, like generics, collections and so on do not come with a run-time cost, only compile time cost (the code will be slower to compile). Any operation on zero-cost abstractions is as fast as you would write out matching functionality by hand using lower-level programming concepts like for loops, counters, ifs and using raw pointers.

Or another way to view this is that using zero-cost abstraction tools, functions, templates, classes and such come with "zero cost" for the performance of your code.