"That makes everything slow, inefficient, and widely dangerous."

There nothing faster and more efficient than building C programs. I also not sure what is dangerous in having libraries. C++ is quite different though.

Of course there is. Raw machine code is the gold standard, and everything else is an attempt to achieve _something_ at the cost of performance, C included, and that's even when considering whole-program optimization and ignoring the overhead introduced by libraries. Other languages with better semantics frequently outperform C (slightly) because the compiler is able to assume more things about the data and instructions being manipulated, generating tighter optimizations.