diff --git a/crates/proof/src/hunspell.rs b/crates/proof/src/hunspell.rs
index 4cf75210..274af9eb 100644
--- a/crates/proof/src/hunspell.rs
+++ b/crates/proof/src/hunspell.rs
@@ -105,7 +105,7 @@ fn search_tiers(lo_exts: Option<&[String]>) -> (Vec<PathBuf>, Vec<PathBuf>) {
                 system.extend(lo_dirs(&base.join("LibreOffice").join("share").join("extensions").to_string_lossy()));
             }
         }
-        system.extend(lo_drive_dirs(lo_exts, Path::is_dir));
+        system.extend(lo_drive_dirs(lo_exts, || LO_DRIVE_BASES.get_or_init(|| lo_drive_bases(Path::is_dir))));
     } else if cfg!(target_os = "macos") {
         if let Some(h) = &home {
             // An app started from Finder or the Dock doesn't see `WORDCRAFT_DICTIONARIES`; this
@@ -136,22 +136,25 @@ fn search_tiers(lo_exts: Option<&[String]>) -> (Vec<PathBuf>, Vec<PathBuf>) {
 }
 
 /// LibreOffice's language folders (`<drive>:\Program Files\LibreOffice\share\extensions\<ext>`)
-/// on the drives C to Z where `is_dir` finds LibreOffice installed. No drive is probed without
+/// on the drives C to Z where LibreOffice is installed (`bases`). No drive is probed without
 /// `lo_exts` (no LibreOffice folders are wanted then).
-fn lo_drive_dirs(lo_exts: Option<&[String]>, is_dir: impl Fn(&Path) -> bool) -> Vec<PathBuf> {
+fn lo_drive_dirs<'a>(lo_exts: Option<&[String]>, bases: impl FnOnce() -> &'a [PathBuf]) -> Vec<PathBuf> {
     let Some(exts) = lo_exts else { return Vec::new() };
-    let mut out = Vec::new();
-    for drive in 'C'..='Z' {
-        for pf in ["Program Files", "Program Files (x86)"] {
-            let base = PathBuf::from(format!(r"{drive}:\{pf}\LibreOffice\share\extensions"));
-            if is_dir(&base) {
-                out.extend(exts.iter().map(|e| base.join(e)));
-            }
-        }
-    }
-    out
+    bases().iter().flat_map(|base| exts.iter().map(|e| base.join(e))).collect()
 }
 
+/// The `LibreOffice\share\extensions` folders on drives C to Z (48 probes).
+fn lo_drive_bases(is_dir: impl Fn(&Path) -> bool) -> Vec<PathBuf> {
+    ('C'..='Z')
+        .flat_map(|drive| ["Program Files", "Program Files (x86)"].map(|pf| PathBuf::from(format!(r"{drive}:\{pf}\LibreOffice\share\extensions"))))
+        .filter(|base| is_dir(base))
+        .collect()
+}
+
+/// [`lo_drive_bases`], probed once per process.
+// ponytail: a LibreOffice installed while the app runs is seen after a restart.
+static LO_DRIVE_BASES: std::sync::OnceLock<Vec<PathBuf>> = std::sync::OnceLock::new();
+
 /// The user's data folder on Linux and the BSDs: `$XDG_DATA_HOME` when it is an absolute path (the
 /// XDG Base Directory spec ignores a relative one), else `~/.local/share`.
 fn xdg_data_home(xdg: Option<std::ffi::OsString>, home: Option<&Path>) -> Option<PathBuf> {
@@ -627,11 +630,20 @@ mod tests {
             probes.set(probes.get() + 1);
             false
         };
-        assert!(lo_drive_dirs(None, count).is_empty());
+        // craft-libs#495 review: the drives are probed once, not on every lookup.
+        let cache = std::sync::OnceLock::new();
+        let cached = || cache.get_or_init(|| lo_drive_bases(count)).as_slice();
+        assert!(lo_drive_dirs(None, cached).is_empty());
         assert_eq!(probes.get(), 0);
         let exts = ["dict-tr".to_string()];
-        let found = lo_drive_dirs(Some(&exts), |p: &Path| p.to_string_lossy().starts_with(r"D:\Program Files\"));
-        assert_eq!(found, [PathBuf::from(r"D:\Program Files\LibreOffice\share\extensions").join("dict-tr")]);
+        assert!(lo_drive_dirs(Some(&exts), cached).is_empty());
+        assert!(lo_drive_dirs(Some(&exts), cached).is_empty());
+        assert_eq!(probes.get(), 48);
+        let found = lo_drive_bases(|p: &Path| p.to_string_lossy().starts_with(r"D:\Program Files\"));
+        assert_eq!(
+            lo_drive_dirs(Some(&exts), || found.as_slice()),
+            [PathBuf::from(r"D:\Program Files\LibreOffice\share\extensions").join("dict-tr")]
+        );
     }
 
     /// Another region's Language pack never beats the system's dictionary of the right region
diff --git a/crates/proof/src/lang.rs b/crates/proof/src/lang.rs
index 85f5b6e6..993e4030 100644
--- a/crates/proof/src/lang.rs
+++ b/crates/proof/src/lang.rs
@@ -147,6 +147,9 @@ impl ProofLang {
             } else {
                 ProofLang::De
             }
+        } else if tag.split_once('@').is_some_and(|(_, m)| m.eq_ignore_ascii_case("latin")) {
+            // POSIX `sr_RS@latin`: the Latin-script language (`sr-latn`).
+            PackLocale::new(&format!("{primary}-latn")).map_or(ProofLang::Other, ProofLang::Pack)
         } else {
             PackLocale::new(tag).map_or(ProofLang::Other, ProofLang::Pack)
         }
@@ -446,6 +449,9 @@ mod tests {
         // craft-libs#482 review: a POSIX charset or modifier with no region.
         assert_tags(&["en.UTF-8", "en@euro"], ProofLang::En);
         assert_tags(&["de.UTF-8"], ProofLang::De);
+        let sr_latn = ProofLang::Pack(PackLocale::new("sr-latn").unwrap());
+        assert_tags(&["sr@latin", "sr_RS@latin", "sr_RS.UTF-8@latin", "sr-Latn"], sr_latn);
+        assert_tags(&["sr", "sr@cyrillic"], ProofLang::Pack(PackLocale::new("sr").unwrap()));
         assert_tags(&["pt", "pt-BR", "PT_br", "pt-BR.UTF-8", "pt-AO", "por"], ProofLang::Pt);
         let pt_pt = ProofLang::Pack(PackLocale::new("pt-pt").unwrap());
         assert_tags(&[" pt-PT ", "pt_PT.UTF-8", "por-PT"], pt_pt);