I think he means two things, mind you I'm not very familiar with Rust, but I've done a lot of safety-critical C/C++, which is sort of like Rust
1. There's a mental cost on the programmer. You have to learn all the ins and outs of things like the "borrow checker" (a Rust concept) and it's on you to understand the rules and how to use them
2. It can slow down compile time. As your program gets bigger, the compiler is doing more work to check that it's valid code, so that will slow you down.
1. There's a mental cost on the programmer. You have to learn all the ins and outs of things like the "borrow checker" (a Rust concept) and it's on you to understand the rules and how to use them
2. It can slow down compile time. As your program gets bigger, the compiler is doing more work to check that it's valid code, so that will slow you down.