diff --git a/crates/ui-egui/src/idle_tests.rs b/crates/ui-egui/src/idle_tests.rs
index 2d4e5757..3c71146d 100644
--- a/crates/ui-egui/src/idle_tests.rs
+++ b/crates/ui-egui/src/idle_tests.rs
@@ -288,3 +288,23 @@ fn an_animated_gif_wakes_only_the_presenter_and_only_at_its_frames() {
     h.app.ui.present = None;
     h.assert_idle("the presenter closed");
 }
+
+#[test]
+fn cjk_names_are_looked_for_in_edits_not_on_every_pan() {
+    let mut s = Session::new();
+    let a = s.execute("shape.rectangle", &json!({"x": 0, "y": 0, "width": 10, "height": 10})).unwrap()["id"].clone();
+    let b = s.execute("shape.rectangle", &json!({"x": 20, "y": 0, "width": 10, "height": 10})).unwrap()["id"].clone();
+    s.execute("node.set", &json!({"id": a, "name": "中文"})).unwrap();
+    let mut h = Harness::new(s);
+    let ctx = h.ctx.clone();
+    assert_eq!(h.app.cjk_needed(&ctx, 0), crate::cjk::HAN, "the first look reads every name");
+    // A pan or zoom changes the revision but not the document: its hundreds of thousands of
+    // names aren't read again (that took 70 ms a frame in a 900 000-layer file).
+    let revision = h.app.session.ds().unwrap().revision;
+    h.run("view.set", json!({"zoom": 2, "cx": 300, "cy": 200}));
+    assert_ne!(h.app.session.ds().unwrap().revision, revision);
+    assert_eq!(h.app.cjk_needed(&ctx, 0), 0);
+    // An edit is read: the layers it changed.
+    h.run("node.set", json!({"id": b, "name": "한국어"}));
+    assert_eq!(h.app.cjk_needed(&ctx, 0), crate::cjk::HANGUL);
+}
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index 613f18f9..059ca364 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -156,6 +156,7 @@ mod windows_tests;
 
 use std::collections::BTreeSet;
 use std::path::PathBuf;
+use std::sync::Arc;
 
 use figcraft_doc::NodeId;
 use figcraft_engine::Session;
@@ -241,6 +242,9 @@ pub enum TitleBar {
 /// How often open documents get an autosave checkpoint (seconds).
 pub const AUTOSAVE_SECS: f64 = 30.0 * 60.0;
 
+/// Most changed layers whose names are checked for CJK scripts one by one (beyond: all of them).
+const CJK_CHANGES: usize = 10_000;
+
 /// How long a toast shows (seconds).
 const TOAST_SECS: f64 = 3.0;
 
@@ -483,8 +487,8 @@ pub struct FigApp {
     /// System faces for scripts the built-in fonts lack were added (after the font scan), with
     /// faces for these CJK scripts ([`cjk`]) in this UI language's order.
     script_fonts: Option<(u8, &'static str)>,
-    /// The tab (uid) and revision whose names were last checked for CJK scripts.
-    cjk_checked: Option<(u64, u64)>,
+    /// The tab (uid) and document version whose names were last checked for CJK scripts.
+    cjk_checked: Option<(u64, Arc<figcraft_doc::Document>)>,
     /// The language preference the UI strings follow (applied when it changes).
     language: Option<String>,
     /// A field had the keyboard when the last frame ended.
@@ -856,11 +860,24 @@ impl FigApp {
             })
         });
         let dragging = ctx.input(|i| i.pointer.any_down());
-        if let Some(d) = self.session.docs.get(self.session.active).filter(|d| !dragging && self.cjk_checked != Some((d.uid, d.revision))) {
-            self.cjk_checked = Some((d.uid, d.revision));
-            let doc = &d.doc;
-            let comments = doc.comments.iter().flat_map(|c| std::iter::once(&c.first).chain(&c.replies)).flat_map(|m| [&m.author, &m.text]);
-            need |= std::iter::once(&doc.name).chain(doc.nodes().map(|n| &n.name)).chain(comments).fold(0, |m, s| m | cjk::scripts(s));
+        // Pans and zooms change the revision too: only a new version of the document is looked
+        // at, and only the layers it changed (a large file has hundreds of thousands of names).
+        let current = self.session.docs.get(self.session.active).filter(|_| !dragging).map(|d| (d.uid, d.doc.clone()));
+        if let Some((uid, doc)) = current {
+            let before = self.cjk_checked.take().filter(|(u, _)| *u == uid).map(|(_, b)| b);
+            if !before.as_ref().is_some_and(|b| Arc::ptr_eq(b, &doc)) {
+                let mut scan = |s: &str| need |= cjk::scripts(s);
+                scan(&doc.name);
+                match before.as_ref().and_then(|b| doc.changed_ids(b, CJK_CHANGES)) {
+                    Some(ids) => ids.into_iter().filter_map(|id| doc.node(id)).for_each(|n| scan(&n.name)),
+                    None => doc.nodes().for_each(|n| scan(&n.name)),
+                }
+                doc.comments.iter().flat_map(|c| std::iter::once(&c.first).chain(&c.replies)).for_each(|m| {
+                    scan(&m.author);
+                    scan(&m.text);
+                });
+            }
+            self.cjk_checked = Some((uid, doc));
         }
         need
     }