diff --git a/Cargo.lock b/Cargo.lock
index dab8310..f05a1d2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -112,6 +112,7 @@ dependencies = [
  "cfg-if",
  "constant_time_eq",
  "cpufeatures",
+ "memmap2",
 ]
 
 [[package]]
@@ -357,7 +358,7 @@ checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
 [[package]]
 name = "diskghost-cli"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "clap",
  "diskghost-core",
@@ -366,7 +367,7 @@ dependencies = [
 
 [[package]]
 name = "diskghost-core"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "blake3",
  "criterion",
@@ -572,6 +573,15 @@ version = "2.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "88904434abc2901f197fe8cc55f0445e7ded921dba5911dad2e2b39b48e663c4"
 
+[[package]]
+name = "memmap2"
+version = "0.9.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d1219ed1b7f229ee7104d281dd01d6802fe28bb6e95d292942c4daacdeb798c0"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
diff --git a/Cargo.toml b/Cargo.toml
index fcefae3..0191f4d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,7 +4,7 @@ exclude = ["gui"]
 resolver = "2"
 
 [workspace.package]
-version = "0.4.0"
+version = "0.5.0"
 edition = "2021"
 license = "MIT"
 authors = ["kingchenc"]
diff --git a/crates/diskghost-core/Cargo.toml b/crates/diskghost-core/Cargo.toml
index 561fa5b..fbcb960 100644
--- a/crates/diskghost-core/Cargo.toml
+++ b/crates/diskghost-core/Cargo.toml
@@ -11,7 +11,7 @@ description = "Fast parallel disk scanning and duplicate detection — the engin
 [dependencies]
 jwalk = "0.8"
 rayon = "1"
-blake3 = "1"
+blake3 = { version = "1", features = ["mmap"] }
 same-file = "1"
 globset = "0.4"
 trash = "5"
diff --git a/crates/diskghost-core/src/lib.rs b/crates/diskghost-core/src/lib.rs
index 429ec72..d4ec6ee 100644
--- a/crates/diskghost-core/src/lib.rs
+++ b/crates/diskghost-core/src/lib.rs
@@ -199,23 +199,36 @@ fn is_excluded(glob: &globset::GlobSet, path: &Path) -> bool {
 fn walk(root: &Path, opts: &Options, progress: &Progress) -> Walk {
     let glob = Arc::new(build_globset(&opts.exclude));
 
-    let mut wd = jwalk::WalkDir::new(root)
+    // Each file's size is cached in the entry's client_state (Some(size), or
+    // None if the stat failed) so it can be read on the parallel walk threads
+    // instead of one-at-a-time in the serial consumer below. This is the
+    // scan's hot path: statting hundreds of thousands of files serially was
+    // the whole cost; jwalk already walks in parallel, so we stat there too.
+    let mut wd = jwalk::WalkDirGeneric::<((), Option<u64>)>::new(root)
         .skip_hidden(false)
         .follow_links(opts.follow_symlinks);
     if let Some(d) = opts.max_depth {
         wd = wd.max_depth(d);
     }
-    if !glob.is_empty() {
+    let glob = glob.clone();
+    let wd = wd.process_read_dir(move |_depth, _path, _state, children| {
         // Prune excluded entries *before* descending, so an excluded directory
         // (e.g. node_modules) costs no I/O for its entire subtree.
-        let glob = glob.clone();
-        wd = wd.process_read_dir(move |_depth, _path, _state, children| {
+        if !glob.is_empty() {
             children.retain(|res| match res {
                 Ok(e) => !is_excluded(&glob, &e.path()),
                 Err(_) => true,
             });
-        });
-    }
+        }
+        // Stat every file here (on the walk's rayon worker), caching its size.
+        for res in children.iter_mut() {
+            if let Ok(e) = res {
+                if e.file_type().is_file() {
+                    e.client_state = std::fs::metadata(e.path()).ok().map(|m| m.len());
+                }
+            }
+        }
+    });
 
     let mut files = Vec::new();
     let mut dirs = 0u64;
@@ -233,9 +246,8 @@ fn walk(root: &Path, opts: &Options, progress: &Progress) -> Walk {
                         dirs += 1; // don't count the root itself
                     }
                 } else if ft.is_file() {
-                    match e.metadata() {
-                        Ok(m) => {
-                            let size = m.len();
+                    match e.client_state {
+                        Some(size) => {
                             progress.files.fetch_add(1, Ordering::Relaxed);
                             progress.bytes.fetch_add(size, Ordering::Relaxed);
                             files.push(FileEntry {
@@ -243,7 +255,7 @@ fn walk(root: &Path, opts: &Options, progress: &Progress) -> Walk {
                                 size,
                             });
                         }
-                        Err(_) => skipped += 1,
+                        None => skipped += 1,
                     }
                 }
             }
@@ -587,12 +599,28 @@ pub fn remove_path(
                 .collect();
             errors.extend(file_errors);
 
-            // Remove directories deepest-first so each is empty when removed.
+            // Remove directories deepest-first. Within a single depth level no
+            // dir contains another, so each level is removed in parallel; the
+            // levels run deepest → shallowest so a dir is always empty when we
+            // reach it.
             dirs.sort_by_key(|d| std::cmp::Reverse(d.components().count()));
-            for d in &dirs {
-                if let Err(e) = std::fs::remove_dir(d) {
-                    errors.push(format!("{}: {e}", d.display()));
+            let mut i = 0;
+            while i < dirs.len() {
+                let depth = dirs[i].components().count();
+                let mut j = i;
+                while j < dirs.len() && dirs[j].components().count() == depth {
+                    j += 1;
                 }
+                let level_errors: Vec<String> = dirs[i..j]
+                    .par_iter()
+                    .filter_map(|d| {
+                        std::fs::remove_dir(d)
+                            .err()
+                            .map(|e| format!("{}: {e}", d.display()))
+                    })
+                    .collect();
+                errors.extend(level_errors);
+                i = j;
             }
         }
     }
@@ -644,6 +672,14 @@ fn hash_prefix(path: &Path, len: usize) -> std::io::Result<[u8; 32]> {
 }
 
 fn hash_file(path: &Path) -> std::io::Result<String> {
+    // Memory-map the file so BLAKE3 reads straight from the page cache with no
+    // buffered-read syscalls or intermediate copies — the fast path for the
+    // large files that dominate full-hash cost.
+    let mut hasher = blake3::Hasher::new();
+    if hasher.update_mmap(path).is_ok() {
+        return Ok(hasher.finalize().to_hex().to_string());
+    }
+    // Fallback: stream the file (mmap unsupported, empty, or a special file).
     let mut hasher = blake3::Hasher::new();
     let mut file = std::fs::File::open(path)?;
     std::io::copy(&mut file, &mut hasher)?;
diff --git a/gui/src-tauri/Cargo.lock b/gui/src-tauri/Cargo.lock
index 4d5390f..a26a322 100644
--- a/gui/src-tauri/Cargo.lock
+++ b/gui/src-tauri/Cargo.lock
@@ -663,7 +663,7 @@ dependencies = [
 
 [[package]]
 name = "diskghost-core"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "blake3",
  "fs4",
@@ -677,7 +677,7 @@ dependencies = [
 
 [[package]]
 name = "diskghost-gui"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "diskghost-core",
  "serde",
@@ -4159,7 +4159,7 @@ dependencies = [
 
 [[package]]
 name = "winapi-i686-pc-windows-gnu"
-version = "0.4.0"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 
@@ -4174,7 +4174,7 @@ dependencies = [
 
 [[package]]
 name = "winapi-x86_64-pc-windows-gnu"
-version = "0.4.0"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
diff --git a/gui/src-tauri/Cargo.toml b/gui/src-tauri/Cargo.toml
index 344fc71..03e19f4 100644
--- a/gui/src-tauri/Cargo.toml
+++ b/gui/src-tauri/Cargo.toml
@@ -4,7 +4,7 @@
 
 [package]
 name = "diskghost-gui"
-version = "0.4.0"
+version = "0.5.0"
 edition = "2021"
 license = "MIT"
 description = "Diskghost desktop GUI (Tauri) — modern disk usage & duplicate finder."
diff --git a/gui/src-tauri/tauri.conf.json b/gui/src-tauri/tauri.conf.json
index 26d5d25..4f8333f 100644
--- a/gui/src-tauri/tauri.conf.json
+++ b/gui/src-tauri/tauri.conf.json
@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "Diskghost",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "identifier": "org.diskghost.app",
   "build": {
     "frontendDist": "../ui"