diff --git a/Cargo.lock b/Cargo.lock
index bb2e9cc..01ee217 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -262,6 +262,12 @@ dependencies = [
  "x11rb",
 ]
 
+[[package]]
+name = "archery"
+version = "1.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "33ca55ee147b1926dbea904f50fe4902494e97bc742205abbbf10c709e43815f"
+
 [[package]]
 name = "arrayref"
 version = "0.3.9"
@@ -1319,6 +1325,7 @@ version = "0.1.0"
 dependencies = [
  "figcraft-color",
  "figcraft-geom",
+ "imbl",
  "serde",
  "serde_json",
  "thiserror 2.0.21",
@@ -2050,6 +2057,28 @@ version = "0.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "65b27460c2c92b037f3f94c538ed9a3342f3fdf923606781629ccb35f82d042a"
 
+[[package]]
+name = "imbl"
+version = "7.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46bad832b9b463ed9398b8506488cc2e3b897a9d44f13af115f382aac71f4fec"
+dependencies = [
+ "archery",
+ "equivalent",
+ "imbl-sized-chunks",
+ "rand_core",
+ "rand_xoshiro",
+ "serde_core",
+ "version_check",
+ "wide",
+]
+
+[[package]]
+name = "imbl-sized-chunks"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a0813be332553f857953298749fa19549e8b61b80589757c29b4e2a804fa9c6"
+
 [[package]]
 name = "indexmap"
 version = "2.14.2"
@@ -3233,6 +3262,15 @@ dependencies = [
  "rand_core",
 ]
 
+[[package]]
+name = "rand_xoshiro"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f703f4665700daf5512dcca5f43afa6af89f09db47fb56be587f80636bda2d41"
+dependencies = [
+ "rand_core",
+]
+
 [[package]]
 name = "range-alloc"
 version = "0.1.5"
@@ -3513,6 +3551,15 @@ version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9774ba4a74de5f7b1c1451ed6cd5285a32eddb5cccb8cc655a4e50009e06477f"
 
+[[package]]
+name = "safe_arch"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96b02de82ddbe1b636e6170c21be622223aea188ef2e139be0a5b219ec215323"
+dependencies = [
+ "bytemuck",
+]
+
 [[package]]
 name = "same-file"
 version = "1.0.6"
@@ -4735,6 +4782,16 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "wide"
+version = "0.7.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ce5da8ecb62bcd8ec8b7ea19f69a51275e91299be594ea5cc6ef7819e16cd03"
+dependencies = [
+ "bytemuck",
+ "safe_arch",
+]
+
 [[package]]
 name = "winapi-util"
 version = "0.1.11"
diff --git a/Cargo.toml b/Cargo.toml
index afcdfb4..f1b0c48 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -34,6 +34,7 @@ serde = { version = "1", features = ["derive", "rc"] }
 serde_json = { version = "1", features = ["float_roundtrip"] }
 log = "0.4"
 proptest = "1"
+imbl = { version = "7", features = ["serde"] }
 
 # rendering / formats
 tiny-skia = "0.12"
diff --git a/crates/doc/Cargo.toml b/crates/doc/Cargo.toml
index af5409d..5609ed8 100644
--- a/crates/doc/Cargo.toml
+++ b/crates/doc/Cargo.toml
@@ -14,3 +14,4 @@ figcraft-color = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
+imbl = { workspace = true }
diff --git a/crates/doc/src/lib.rs b/crates/doc/src/lib.rs
index 8776d78..8588ba2 100644
--- a/crates/doc/src/lib.rs
+++ b/crates/doc/src/lib.rs
@@ -65,6 +65,16 @@ pub enum DocError {
 
 pub type DocResult<T> = Result<T, DocError>;
 
+/// The set of touched node ids. Never part of equality or serialisation.
+#[derive(Clone, Debug, Default)]
+pub struct Dirty(pub std::collections::BTreeSet<NodeId>);
+
+impl PartialEq for Dirty {
+    fn eq(&self, _: &Self) -> bool {
+        true
+    }
+}
+
 /// Raw image bytes (encoded PNG/JPEG/…) kept by content hash.
 #[derive(Clone, Debug, PartialEq)]
 pub struct ImageData {
@@ -79,7 +89,10 @@ pub struct Document {
     pub name: String,
     /// Page ids in order.
     pub pages: Vec<NodeId>,
-    nodes: BTreeMap<NodeId, Arc<Node>>,
+    nodes: imbl::OrdMap<NodeId, Arc<Node>>,
+    /// Nodes touched since the last [`take_dirty`](Self::take_dirty) (edited, added or removed).
+    #[serde(skip)]
+    dirty: Dirty,
     next_id: u64,
     #[serde(default)]
     pub styles: Vec<Style>,
@@ -108,7 +121,8 @@ impl Document {
         let mut doc = Self {
             name: name.into(),
             pages: Vec::new(),
-            nodes: BTreeMap::new(),
+            nodes: imbl::OrdMap::new(),
+            dirty: Dirty::default(),
             next_id: 1,
             styles: Vec::new(),
             variables: Variables::default(),
@@ -121,6 +135,16 @@ impl Document {
         doc
     }
 
+    /// Node ids touched since the last call (edited, added or removed), clearing the record.
+    pub fn take_dirty(&mut self) -> std::collections::BTreeSet<NodeId> {
+        std::mem::take(&mut self.dirty.0)
+    }
+
+    /// Node ids touched so far (without clearing).
+    pub fn dirty(&self) -> &std::collections::BTreeSet<NodeId> {
+        &self.dirty.0
+    }
+
     /// A fresh unused id.
     pub fn alloc_id(&mut self) -> NodeId {
         let id = NodeId(self.next_id);
@@ -138,7 +162,11 @@ impl Document {
 
     /// Mutable access (copy-on-write when a snapshot shares the node).
     pub fn node_mut(&mut self, id: NodeId) -> Option<&mut Node> {
-        self.nodes.get_mut(&id).map(Arc::make_mut)
+        let n = self.nodes.get_mut(&id).map(Arc::make_mut);
+        if n.is_some() {
+            self.dirty.0.insert(id);
+        }
+        n
     }
 
     pub fn get(&self, id: NodeId) -> DocResult<&Node> {
@@ -177,6 +205,7 @@ impl Document {
             0.0,
         );
         self.nodes.insert(id, Arc::new(node));
+        self.dirty.0.insert(id);
         self.pages.push(id);
         id
     }
@@ -214,6 +243,7 @@ impl Document {
         }
         node.parent = Some(parent);
         self.nodes.insert(id, Arc::new(node));
+        self.dirty.0.insert(id);
         let p = self.get_mut(parent)?;
         let at = index.unwrap_or(p.children.len()).min(p.children.len());
         p.children.insert(at, id);
@@ -294,6 +324,7 @@ impl Document {
         }
         for d in self.subtree(id) {
             self.nodes.remove(&d);
+            self.dirty.0.insert(d);
         }
         Ok(())
     }
@@ -511,6 +542,7 @@ impl Document {
                 self.next_id = new_id.0.saturating_add(1);
             }
             self.nodes.insert(*new_id, Arc::new(c));
+            self.dirty.0.insert(*new_id);
         }
         let p = self.get_mut(parent)?;
         let at = index.unwrap_or(p.children.len()).min(p.children.len());
@@ -593,7 +625,7 @@ impl Document {
     /// Check structural invariants (used by tests and after loading untrusted files).
     pub fn validate(&self) -> Vec<String> {
         let mut issues = Vec::new();
-        for (id, n) in &self.nodes {
+        for (id, n) in self.nodes.iter() {
             if n.id != *id {
                 issues.push(format!("node key {id} has id {}", n.id));
             }
@@ -653,7 +685,7 @@ impl Document {
             }
         }
         self.pages.retain(|p| self.nodes.get(p).is_some_and(|n| n.is_page()));
-        for (k, n) in &self.nodes {
+        for (k, n) in self.nodes.iter() {
             if n.is_page() && !self.pages.contains(k) {
                 self.pages.push(*k);
             }
diff --git a/crates/engine/src/cmd/edit.rs b/crates/engine/src/cmd/edit.rs
index a8b2a92..6f27056 100644
--- a/crates/engine/src/cmd/edit.rs
+++ b/crates/engine/src/cmd/edit.rs
@@ -252,7 +252,8 @@ pub fn specs() -> Vec<CommandSpec> {
                 Some(Value::Array(a)) => {
                     let mut out = Vec::new();
                     for (i, c) in a.iter().enumerate() {
-                        let cmd = c.get("command").and_then(Value::as_str).ok_or_else(|| bad("command.batch", format!("step {i} has no `command`")))?;
+                        let cmd =
+                            c.get("command").and_then(Value::as_str).ok_or_else(|| bad("command.batch", format!("step {i} has no `command`")))?;
                         out.push((cmd.to_string(), c.get("params").cloned().unwrap_or(json!({}))));
                     }
                     out
diff --git a/crates/engine/src/components.rs b/crates/engine/src/components.rs
index e146781..a9b3259 100644
--- a/crates/engine/src/components.rs
+++ b/crates/engine/src/components.rs
@@ -344,7 +344,7 @@ fn diff_groups(a: &Node, b: &Node) -> Vec<&'static str> {
 }
 
 /// After an edit: record overrides inside instances, then rebuild instances of edited components.
-pub fn sync_after_edit(doc: &mut Document, before: &Document, changed: &[NodeId]) {
+pub fn sync_after_edit(doc: &mut Document, before: &Document, changed: &[NodeId], touched: &BTreeSet<NodeId>) {
     // 1. Overrides for layers edited inside instances.
     for id in changed {
         let Some(n) = doc.node(*id) else { continue };
@@ -389,7 +389,7 @@ pub fn sync_after_edit(doc: &mut Document, before: &Document, changed: &[NodeId]
             comps.insert(c);
         }
     }
-    for id in before.ids() {
+    for &id in touched {
         if !doc.contains(id)
             && let Some(c) = owning_component(before, id)
             && doc.contains(c)
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index 264e63c..29180fc 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -620,8 +620,9 @@ pub fn changed_nodes(doc: &Document, before: &Document) -> Vec<NodeId> {
 /// Keep derived state consistent after edits: text boxes resize to their content, groups wrap
 /// their children, instances follow their main components, auto layout re-flows.
 pub fn normalize(doc: &mut Document, before: &Document) {
-    let changed = changed_nodes(doc, before);
-    if changed.is_empty() && doc.node_count() == before.node_count() {
+    // Only what was touched since the last normalisation (edited, added or removed).
+    let mut touched: BTreeSet<NodeId> = doc.take_dirty();
+    if touched.is_empty() {
         return;
     }
     let m = measure::TextMeasure;
@@ -633,21 +634,28 @@ pub fn normalize(doc: &mut Document, before: &Document) {
             cmd::styles::propagate_style(doc, &sid);
         }
     }
-    let changed = changed_nodes(doc, before);
+    touched.extend(doc.take_dirty());
+    let live = |doc: &Document, t: &BTreeSet<NodeId>| -> Vec<NodeId> { t.iter().copied().filter(|i| doc.contains(*i)).collect() };
     // 1. Text auto-size.
-    for id in &changed {
-        let Some(n) = doc.node(*id) else { continue };
+    for id in live(doc, &touched) {
+        let Some(n) = doc.node(id) else { continue };
         if let Some((w, h)) = figcraft_text::auto_size(n)
             && ((w - n.width).abs() > 1e-6 || (h - n.height).abs() > 1e-6)
         {
-            figcraft_layout::set_size(doc, *id, w, h);
+            figcraft_layout::set_size(doc, id, w, h);
         }
     }
+    touched.extend(doc.take_dirty());
     // 2. Instances follow edited main components (and record overrides inside instances).
-    components::sync_after_edit(doc, before, &changed);
+    let changed = live(doc, &touched);
+    components::sync_after_edit(doc, before, &changed, &touched);
+    touched.extend(doc.take_dirty());
+    // Parents of removed nodes (as they were before) count as touched.
+    let removed_parents: Vec<NodeId> =
+        touched.iter().filter(|i| !doc.contains(**i)).filter_map(|i| before.node(*i).and_then(|n| n.parent)).filter(|p| doc.contains(*p)).collect();
     // 3. Groups / booleans wrap their children.
     let mut fit: BTreeSet<NodeId> = BTreeSet::new();
-    for id in changed_nodes(doc, before) {
+    for id in live(doc, &touched).into_iter().chain(removed_parents.iter().copied()) {
         if doc.node(id).is_some_and(|n| n.kind.bounds_follow_children()) {
             fit.insert(id);
         }
@@ -659,56 +667,37 @@ pub fn normalize(doc: &mut Document, before: &Document) {
             }
         }
     }
-    // Removed children change their parents too.
-    for id in before.ids() {
-        if !doc.contains(id)
-            && let Some(p) = before.node(id).and_then(|n| n.parent)
-            && doc.node(p).is_some_and(|n| n.kind.bounds_follow_children())
-        {
-            fit.insert(p);
-        }
-    }
-    // Deepest first.
     let mut fit: Vec<NodeId> = fit.into_iter().collect();
     fit.sort_by_key(|id| std::cmp::Reverse(doc.ancestors(*id).len()));
     for id in fit {
         if doc.node(id).is_some_and(|n| n.children.is_empty()) {
-            // Empty groups disappear, like Figma.
+            // Empty groups disappear, like the incumbent.
             let _ = doc.remove(id);
         } else {
             let _ = doc.fit_to_children(id);
         }
     }
+    touched.extend(doc.take_dirty());
     // 4. Auto layout for affected frames.
     let mut frames: BTreeSet<NodeId> = BTreeSet::new();
-    let changed = changed_nodes(doc, before);
-    for id in &changed {
-        let mut chain = vec![*id];
-        chain.extend(doc.ancestors(*id));
+    for id in live(doc, &touched).into_iter().chain(removed_parents) {
+        if !doc.contains(id) {
+            continue;
+        }
+        let mut chain = vec![id];
+        chain.extend(doc.ancestors(id));
         for c in chain {
             if doc.node(c).is_some_and(|n| n.layout.is_some()) {
                 frames.insert(c);
             }
         }
     }
-    for id in before.ids() {
-        if !doc.contains(id)
-            && let Some(p) = before.node(id).and_then(|n| n.parent)
-        {
-            let mut chain = vec![p];
-            chain.extend(doc.ancestors(p));
-            for c in chain {
-                if doc.node(c).is_some_and(|n| n.layout.is_some()) {
-                    frames.insert(c);
-                }
-            }
-        }
-    }
     let mut frames: Vec<NodeId> = frames.into_iter().collect();
     frames.sort_by_key(|id| std::cmp::Reverse(doc.ancestors(*id).len()));
     for f in frames {
         figcraft_layout::layout_frame(doc, f, &m);
     }
+    doc.take_dirty();
 }
 
 #[cfg(test)]
diff --git a/crates/render/src/draw.rs b/crates/render/src/draw.rs
index 0316c1c..689c9ab 100644
--- a/crates/render/src/draw.rs
+++ b/crates/render/src/draw.rs
@@ -370,7 +370,8 @@ pub fn draw_node(ctx: &Ctx, pix: &mut Pixmap, id: NodeId, parent_xf: Affine, dep
                 // Work in a padded buffer: everything beyond the layer is "outside the shape", so
                 // the blur pulls shadow in from every edge, not just the offset side.
                 let (dx, dy) = (s.offset.0 * ctx.scale, s.offset.1 * ctx.scale);
-                let pad = ((s.radius / 2.0 * ctx.scale * 3.0) + s.spread.abs() * ctx.scale + dx.abs().max(dy.abs())).ceil().clamp(0.0, 2048.0) as u32 + 2;
+                let pad =
+                    ((s.radius / 2.0 * ctx.scale * 3.0) + s.spread.abs() * ctx.scale + dx.abs().max(dy.abs())).ceil().clamp(0.0, 2048.0) as u32 + 2;
                 let Some(mut big) = Pixmap::new(lw.max(1) + pad * 2, lh.max(1) + pad * 2) else { continue };
                 big.fill(tiny_skia::Color::WHITE);
                 let ox = pad as f32 + dx as f32;
@@ -387,7 +388,14 @@ pub fn draw_node(ctx: &Ctx, pix: &mut Pixmap, id: NodeId, parent_xf: Affine, dep
                 fx::morph(&mut big, (s.spread * ctx.scale).round() as i32);
                 fx::blur(&mut big, s.radius / 2.0 * ctx.scale);
                 let Some(mut cropped) = Pixmap::new(lw.max(1), lh.max(1)) else { continue };
-                cropped.draw_pixmap(-(pad as i32), -(pad as i32), big.as_ref(), &PixmapPaint { blend_mode: tiny_skia::BlendMode::Source, ..Default::default() }, Transform::identity(), None);
+                cropped.draw_pixmap(
+                    -(pad as i32),
+                    -(pad as i32),
+                    big.as_ref(),
+                    &PixmapPaint { blend_mode: tiny_skia::BlendMode::Source, ..Default::default() },
+                    Transform::identity(),
+                    None,
+                );
                 let shifted = &mut cropped;
                 fx::mask_by(shifted, &sa, false);
                 fx::tint(shifted, [s.color.r, s.color.g, s.color.b, s.color.a]);