adding regex-automata to cargo.toml file reduces performance

[vvmikheev]

Hello.
I have met some weird problems with the latest 1.10.5 regex release.

After the upgrade I have encountered some serious performance problems with regular expressions compilation.
After hours of debugging I have noticed kinda unexpected behavior - adding regex-automata crate to Cargo.toml file somehow affects the regex performance (makes it several times worse).

MRE:

use std::time::Instant;
use regex::Regex;

fn main() {
    let now = Instant::now();
    for _ in 0..10000 {
        Regex::new("some.regex").unwrap();
    }
    println!("took {}ms", now.elapsed().as_millis());
}

Cargo.toml file:

[package]
name = "testy"
version = "0.1.0"
edition = "2021"

[dependencies]
regex = "1.10.5"
regex-automata = "0.4.7" # <-- remove this guy to see the difference! 

I understand that regex-automata is in the dependencies of regex. Moreover - the only thing that is changed in Cargo.lock file is the list of dependencies of the testy crate. But on my computer this program takes like 3 second without explicit regex-automata and 18 seconds with it.