Set-up rayon

Cargo.lock

@@ -243,6 +243,7 @@ dependencies = [
  "log",
  "pdf-writer",
  "pretty_env_logger",
+ "rayon",
  "walkdir",
  "zip",
 ]

Cargo.toml

@@ -9,5 +9,6 @@ image = "0.25.2"
 log = "0.4.22"
 pdf-writer = "0.12.0"
 pretty_env_logger = "0.5.0"
+rayon = "1.10.0"
 walkdir = "2.5.0"
 zip = "2.2.0"

src/main.rs

@@ -1,6 +1,7 @@
 use clap::{Parser, ValueHint};
 use log::info;
 use pdf_writer::{Content, Filter, Finish, Name, Pdf, Rect, Ref};
+use rayon::prelude::*;
 use std::ffi::OsStr;
 use std::fs::File;
 use std::io::Read;
@@ -79,7 +80,7 @@ fn convert_cbz(cbz_path: &Path, output_dir: &Path) -> Result<(), Box<dyn std::er
         }
     }
 
-    images.sort_by_key(|img| img.name.clone());
+    images.par_sort_by_key(|img| img.name.clone());
 
     let mut pdf = Pdf::new();
     let catalog_id = Ref::new(1);