In Rust, abstractions tend to be zero-cost, but things that actually impact runtime are as fast as you write them.

Concurrency problems don't magically disappear because your language can check for them. You still need to use memory-safe patterns, but the compiler will force your hand and prevent you from doing unsafe things accidentally.

In the end, this makes it far easier to build correct, concurrent applications. If you decide to try some fancy new pattern that doesn't require locking, the compiler can guarantee the memory safety of your new implementation.