> The problem is that C have practically no checks, so any safety checks put into the competing language will have a runtime cost, which often is unacceptable.

This problem is overstated. There's no safety/performance tradeoff here. Rust has shown that extensive safety checks can be applied at compile time with zero runtime overhead.

For a concrete example, checking that an array access is in bounds at runtime does come with a performance penalty. However it's also possible to prove at compile time that an array index can never escape it's array bounds. And, if it's not possible to prove this statically - you should be heavily questioning the security of that code.