diff --git a/upload-api/migration-sitecore/libs/extractLocales.js b/upload-api/migration-sitecore/libs/extractLocales.js
index f99ae48e5..3b1d5995e 100644
--- a/upload-api/migration-sitecore/libs/extractLocales.js
+++ b/upload-api/migration-sitecore/libs/extractLocales.js
@@ -1,78 +1,181 @@
 /* eslint-disable @typescript-eslint/no-var-requires */
-const fs = require('fs');
-const path = require('path');
-
-const extractLocales = (dir) => {
-  console.info('🔍 [DEBUG] extractLocales - Starting locale extraction from:', dir);
-  console.time('🔍 [DEBUG] extractLocales - Total extraction time');
-
-  // ✅ Create a new Set for each function call instead of using global
-  const uniqueLanguages = new Set();
-  let fileCount = 0;
-  let processedFiles = 0;
-
-  const extractRecursive = (currentDir) => {
-    try {
-      const items = fs?.readdirSync?.(currentDir, { withFileTypes: true });
-
-      for (const item of items) {
-        const fullPath = path?.join?.(currentDir, item?.name);
-
-        if (item?.isDirectory()) {
-          // ✅ Skip certain directories that are unlikely to contain locale data
-          const skipDirs = [
-            '__Standard Values',
-            '__Prototypes',
-            '__Masters',
-            'blob',
-            'media library'
-          ];
-          if (!skipDirs.some((skipDir) => item.name.includes(skipDir))) {
-            extractRecursive(fullPath);
-          }
-        } else if (item?.isFile() && item?.name === 'data.json') {
-          fileCount++;
-          try {
-            const rawData = fs?.readFileSync?.(fullPath, 'utf8');
-            const jsonData = JSON?.parse?.(rawData);
-            const language = jsonData?.item?.$?.language;
-
-            if (language) {
-              uniqueLanguages?.add?.(language);
-              processedFiles++;
-              console.info(
-                `🔍 [DEBUG] extractLocales - Found locale: "${language}" in ${fullPath}`
-              );
-            }
-          } catch (error) {
-            console.error(`🔍 [DEBUG] extractLocales - Error reading ${fullPath}:`, error?.message);
-          }
-
-          // ✅ Progress logging every 100 files
-          if (fileCount % 100 === 0) {
-            console.info(
-              `🔍 [DEBUG] extractLocales - Progress: ${fileCount} files scanned, ${uniqueLanguages.size} unique locales found`
-            );
-          }
-        }
+const fs = require("fs");
+const path = require("path");
+
+// ─── tunables ────────────────────────────────────────────────────────────────
+const HEAD_BYTES = 131_072; // 128 KiB – covers item.$.language in all known exports
+const CONCURRENCY = Number(process.env.LOCALE_CONCURRENCY) || 24;
+const DEBUG = process.env.DEBUG_SITECORE_LOCALES === "1";
+
+// Fast-path: find the "$" metadata block first, then extract language from it.
+// This avoids matching a "language" key that belongs to nested field content.
+//
+// Strategy:
+//   1. Find the first  "$":  {  block in the head window (where item.$ lives)
+//   2. Extract up to 512 chars after it (enough to cover all metadata keys)
+//   3. Match "language" only within that narrow slice
+//
+// Fallback to full JSON.parse handles any file where this doesn't match.
+const META_BLOCK_RE = /"\$"\s*:\s*\{([^}]{1,512})\}/;
+const LANG_IN_META_RE = /"language"\s*:\s*"([^"]{1,64})"/;
+
+// Hoisted once – never recreated in the hot path
+// Combines your original Sitecore system dirs + filesystem noise dirs
+const SKIP_DIRS = new Set([
+  "__Standard Values",
+  "__Prototypes",
+  "__Masters",
+  "blob",
+  "media library",
+  "node_modules",
+  ".git",
+  "__MACOSX",
+]);
+
+// ─── phase 1: collect all data.json paths ────────────────────────────────────
+
+async function collectPaths(dir, results = []) {
+  if (dir == null || typeof dir !== "string" || dir?.length === 0) {
+    console.error("[extractLocales] collectPaths: invalid or empty dir");
+    return results;
+  }
+
+  let entries;
+  try {
+    entries = await fs.promises.readdir(dir, { withFileTypes: true });
+  } catch (err) {
+    console.error(`[extractLocales] cannot read dir ${dir}:`, err?.message ?? err);
+    return results;
+  }
+
+  const subdirs = [];
+
+  for (const entry of entries) {
+    const name = entry?.name;
+    if (typeof name !== "string") continue;
+
+    // Match your original logic: skip if any skipDir is a substring of the name
+    if ([...SKIP_DIRS].some((s) => name.includes(s))) continue;
+
+    const full = path.join(dir, name);
+
+    if (entry?.isDirectory?.()) {
+      subdirs.push(full);
+    } else if (entry?.isFile?.() && name === "data.json") {
+      results.push(full);
+    }
+  }
+
+  await Promise.all(subdirs.map((d) => collectPaths(d, results)));
+  return results;
+}
+
+// ─── phase 2: extract language from one file ─────────────────────────────────
+
+async function extractLanguage(filePath) {
+  if (filePath == null || typeof filePath !== "string" || filePath.length === 0) {
+    return null;
+  }
+
+  let fd;
+  try {
+    // Fast path — read only the first 128 KiB
+    fd = await fs.promises.open(filePath, "r");
+    const buf = Buffer.allocUnsafe(HEAD_BYTES);
+    const { bytesRead } = await fd.read(buf, 0, HEAD_BYTES, 0);
+    await fd.close();
+    fd = null;
+
+    const head = buf.toString("utf8", 0, bytesRead);
+    const block = META_BLOCK_RE.exec(head);
+    const metaSlice = block != null && block[1] != null ? block[1] : null;
+    const m = metaSlice != null ? LANG_IN_META_RE.exec(metaSlice) : null;
+
+    if (m != null && m[1] != null && m[1] !== "") {
+      if (DEBUG) console.debug(`[fast]     ${filePath} → ${m[1]}`);
+      return m[1];
+    }
+
+    // Fallback — full parse (identical to original behaviour)
+    if (DEBUG) console.debug(`[fallback] ${filePath}`);
+    const raw = await fs.promises.readFile(filePath, "utf8");
+    const json = JSON.parse(raw);
+    return json?.item?.$?.language ?? null;
+
+  } catch (err) {
+    console.error(`[extractLocales] error reading ${filePath}:`, err?.message ?? err);
+    return null;
+  } finally {
+    if (fd) await fd.close().catch(() => { });
+  }
+}
+
+// ─── phase 3: bounded-concurrency processing ─────────────────────────────────
+
+async function processWithConcurrency(paths, concurrency) {
+  const locales = new Set();
+  if (!Array.isArray(paths)) {
+    return locales;
+  }
+
+  const limit = Math.max(1, Number(concurrency) || CONCURRENCY);
+  const total = paths?.length;
+  let idx = 0;
+  let scanned = 0;
+
+  async function worker() {
+    while (idx < paths?.length) {
+      const filePath = paths[idx++];
+      if (filePath == null || typeof filePath !== "string") continue;
+      const lang = await extractLanguage(filePath);
+      if (lang) locales.add(lang);
+      scanned++;
+      if (scanned % 100 === 0) {
+        console.info(
+          `[extractLocales] progress: ${scanned}/${total} files scanned, ${locales.size} unique locale(s) found`
+        );
       }
-    } catch (error) {
-      console.error(
-        `🔍 [DEBUG] extractLocales - Error reading directory ${currentDir}:`,
-        error?.message
-      );
     }
-  };
+  }
+
+  await Promise.all(
+    Array.from({ length: Math.min(limit, paths.length) }, worker)
+  );
+
+  return locales;
+}
+
+// ─── public API ──────────────────────────────────────────────────────────────
+
+/**
+ * Walk `dir` and return a Set of all unique locale strings found in data.json files.
+ * Async drop-in replacement for the original synchronous version.
+ *
+ * @param   {string}           dir
+ * @returns {Promise<Set<string>>}
+ */
+const extractLocales = async (dir) => {
+  const empty = new Set();
+  if (dir == null || typeof dir !== "string" || dir?.length === 0) {
+    console.error("[extractLocales] invalid or empty dir; returning empty locale set");
+    return empty;
+  }
+
+  console.info("[extractLocales] starting locale extraction from:", dir);
+  console.time("[extractLocales] total extraction time");
+
+  const paths = await collectPaths(dir);
+  console.info(`[extractLocales] found ${paths.length} data.json files`);
 
-  extractRecursive(dir);
+  const locales = await processWithConcurrency(paths, CONCURRENCY);
 
-  console.timeEnd('🔍 [DEBUG] extractLocales - Total extraction time');
+  console.timeEnd("[extractLocales] total extraction time");
   console.info(
-    `🔍 [DEBUG] extractLocales - Final results: ${fileCount} total files scanned, ${processedFiles} files with locale data, ${uniqueLanguages.size} unique locales found`
+    `[extractLocales] done — ${paths.length} files scanned, ${locales.size} unique locale(s):`,
+    Array.from(locales)
   );
-  console.info('🔍 [DEBUG] extractLocales - Unique locales:', Array.from(uniqueLanguages));
 
-  return uniqueLanguages;
+  return locales;
 };
 
-module.exports = extractLocales;
+module.exports = extractLocales;
\ No newline at end of file