The problem is not with C the language, but with the C standard library, which has many inefficiency warts. Examples: * Strings. Any form of string access othe

The problem is not with C the language, but with the C standard library, which has many inefficiency warts. Examples: * Strings. Any form of string access other than scanning the string's characters one by one from start to finish can benefit from knowing the string's length in advance. In C++, std::string and std::string_view know their lengths; plain C strings don't. Thus, in performance-optimal plain C, almost any function that takes a string parameter ought to also take the string length as a separate parameter - but most C standard library functions neglect to do so. * Callbacks. When the callback is static, you want to give the compiler the opportunity to inline it into the call site. In C++, this is natural: pass the callback as a template parameter. In performance-optimal C, you'd want to provide macro version of functions that take callbacks. But the C standard library only supports callbacks as function pointers (e.g. in bsearch(3), qsort(3) etc.), which means unnecessary pointer dereferences and which makes inlining impossible.