diff --git a/README.md b/README.md
index c20df5d..2fd914c 100644
--- a/README.md
+++ b/README.md
@@ -260,6 +260,7 @@ Once registered you can define the dockerfile to use with `-f Dockerfile.aarch64
 
 ## Versions
 
+* **16.09.21:** - Fix slow `chown` on large workspace (contents of workspace folder no longer chowned).
 * **11.07.21:** - Bump node to 14 to fix builds
 * **08.05.21:** - Fix doc link
 * **04.02.20:** - Allow setting gui password via hash using env var `HASHED_PASSWORD`.
diff --git a/readme-vars.yml b/readme-vars.yml
index 08dbd39..2fea39f 100644
--- a/readme-vars.yml
+++ b/readme-vars.yml
@@ -75,6 +75,7 @@ app_setup_block: |
 
 # changelog
 changelogs:
+  - { date: "16.09.21:", desc: "Fix slow `chown` on large workspace (contents of workspace folder no longer chowned)." }
   - { date: "11.07.21:", desc: "Bump node to 14 to fix builds" }
   - { date: "08.05.21:", desc: "Fix doc link" }
   - { date: "04.02.20:", desc: "Allow setting gui password via hash using env var `HASHED_PASSWORD`." }
diff --git a/root/etc/cont-init.d/30-config b/root/etc/cont-init.d/30-config
index b3f6cd4..1c09036 100644
--- a/root/etc/cont-init.d/30-config
+++ b/root/etc/cont-init.d/30-config
@@ -18,5 +18,20 @@ if [ -n "${SUDO_PASSWORD}" ] || [ -n "${SUDO_PASSWORD_HASH}" ]; then
 fi
 
 # permissions
-chown -R abc:abc \
-    /config
+if [ -f "/usr/bin/find" ] && [ -f "/usr/bin/xargs" ]; then
+    CORES=$(nproc --all)
+
+    # Split workload between config and workspace
+    echo "setting permissions::configuration"
+    find /config -path /config/workspace -prune -false -o -type d -print0 | \
+        xargs --null -r --max-args=1 --max-procs=$((CORES*2*8)) \
+        chown -R abc:abc
+
+    echo "setting permissions::workspace"
+    chown abc:abc /config/workspace
+else
+    # Set permissions on data mount
+    # do not decend into the workspace
+    chown -R abc:abc "$(ls /config -I workspace)"
+    chown abc:abc /config/workspace
+fi