Rust to_string vs clone performance comparison

rust-to_string-vs-clone.md

// main.rs

use std::time::Instant;

fn main() {
    let instant = Instant::now();
    let text = "".to_string();
    for _ in 1..100000000 {
        let _ = text.to_string();
        // let _ = text.clone();
    }
    println!("Elapsed time: {:.2?}", instant.elapsed());
}

Output(debug):

# to_string()
~> cargo run
   Compiling hoge v0.1.0 (/home/kazuya/sandbox/20240710_184338/hoge)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.11s
     Running `target/debug/hoge`
Elapsed time: 1.44s

# clone()
~> cargo run
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/hoge`
Elapsed time: 1.39s

In debug build, clone() is slightly faster.

Output(release):

# to_string()
~> cargo run --release
   Compiling hoge v0.1.0 (/home/kazuya/sandbox/20240710_184338/hoge)
    Finished `release` profile [optimized] target(s) in 0.09s
     Running `target/release/hoge`
Elapsed time: 316.68ms

# clone()
~> cargo run --release
    Finished `release` profile [optimized] target(s) in 0.00s
     Running `target/release/hoge`
Elapsed time: 317.22ms

No signinicant difference release build.

Tried many times and the result didn't change.