@@ -98,9 +98,27 @@ pub(crate) fn diff(
9898 return;
9999 }
100100
101− let new = cached_set.get(new.id);
102− let old = cached_set.get(old.id);
103− diff(cached_set, change_list, registry, old, new, cached_roots);
101+ let (new, new_template) = cached_set.get(new.id);
102+ let (old, old_template) = cached_set.get(old.id);
103+ if new_template == old_template {
104+ // If they are both using the same template, then just diff the
105+ // subtrees.
106+ diff(cached_set, change_list, registry, old, new, cached_roots);
107+ } else {
108+ // Otherwise, they are probably different enough that
109+ // re-constructing the subtree from scratch should be faster.
110+ // This doubly holds true if we have a new template.
111+ change_list.commit_traversal();
112+ create_and_replace(
113+ cached_set,
114+ change_list,
115+ registry,
116+ new_template,
117+ old,
118+ new,
119+ cached_roots,
120+ );
121+ }
104122 }
105123
106124 // New cached node when the old node was not cached. In this scenario,
@@ -109,10 +127,16 @@ pub(crate) fn diff(
109127 (&NodeKind::Cached(ref c), _) => {
110128 change_list.commit_traversal();
111129 cached_roots.insert(c.id);
112− let new = cached_set.get(c.id);
113− create(cached_set, change_list, registry, new, cached_roots);
114− registry.remove_subtree(&old);
115− change_list.replace_with();
130+ let (new, new_template) = cached_set.get(c.id);
131+ create_and_replace(
132+ cached_set,
133+ change_list,
134+ registry,
135+ new_template,
136+ old,
137+ new,
138+ cached_roots,
139+ );
116140 }
117141
118142 // Old cached node and new non-cached node. Again, assume that they are
@@ -239,6 +263,35 @@ fn diff_children(
239263 return;
240264 }
241265
266+ if new.len() == 1 {
267+ match (old.first(), &new[0]) {
268+ (
269+ Some(&Node {
270+ kind: NodeKind::Text(TextNode { text: old_text }),
271+ }),
272+ &Node {
273+ kind: NodeKind::Text(TextNode { text: new_text }),
274+ },
275+ ) if old_text == new_text => {
276+ // Don't take this fast path...
277+ }
278+ (
279+ _,
280+ &Node {
281+ kind: NodeKind::Text(TextNode { text }),
282+ },
283+ ) => {
284+ change_list.commit_traversal();
285+ change_list.set_text(text);
286+ for o in old {
287+ registry.remove_subtree(o);
288+ }
289+ return;
290+ }
291+ (_, _) => {}
292+ }
293+ }
294+
242295 if old.is_empty() {
243296 if !new.is_empty() {
244297 change_list.commit_traversal();
@@ -926,8 +979,147 @@ fn create(
926979 }
927980 NodeKind::Cached(ref c) => {
928981 cached_roots.insert(c.id);
929− let node = cached_set.get(c.id);
930− create(cached_set, change_list, registry, node, cached_roots)
982+ let (node, template) = cached_set.get(c.id);
983+ if let Some(template) = template {
984+ create_with_template(
985+ cached_set,
986+ change_list,
987+ registry,
988+ template,
989+ node,
990+ cached_roots,
991+ );
992+ } else {
993+ create(cached_set, change_list, registry, node, cached_roots);
994+ }
995+ }
996+ }
997+}
998+
999+// Get or create the template.
1000+//
1001+// Upon entering this function the change list stack may be in any shape:
1002+//
1003+// [...]
1004+//
1005+// When this function returns, it leaves a freshly cloned copy of the template
1006+// on the top of the change list stack:
1007+//
1008+// [... template]
1009+#[inline]
1010+fn get_or_create_template<'a>(
1011+ cached_set: &'a CachedSet,
1012+ change_list: &mut ChangeListBuilder,
1013+ registry: &mut EventsRegistry,
1014+ cached_roots: &mut FxHashSet<CacheId>,
1015+ template_id: CacheId,
1016+) -> (&'a Node<'a>, bool) {
1017+ let (template, template_template) = cached_set.get(template_id);
1018+ debug_assert!(
1019+ template_template.is_none(),
1020+ "templates should not be templated themselves"
1021+ );
1022+
1023+ // If we haven't already created and saved the physical DOM subtree for this
1024+ // template, do that now.
1025+ if change_list.has_template(template_id) {
1026+ // Clone the template and push it onto the stack.
1027+ //
1028+ // [...]
1029+ change_list.push_template(template_id);
1030+ // [... template]
1031+
1032+ (template, true)
1033+ } else {
1034+ // [...]
1035+ create(cached_set, change_list, registry, template, cached_roots);
1036+ // [... template]
1037+ change_list.save_template(template_id);
1038+ // [... template]
1039+
1040+ (template, false)
1041+ }
1042+}
1043+
1044+fn create_and_replace(
1045+ cached_set: &CachedSet,
1046+ change_list: &mut ChangeListBuilder,
1047+ registry: &mut EventsRegistry,
1048+ new_template: Option<CacheId>,
1049+ old: &Node,
1050+ new: &Node,
1051+ cached_roots: &mut FxHashSet<CacheId>,
1052+) {
1053+ debug_assert!(change_list.traversal_is_committed());
1054+
1055+ if let Some(template_id) = new_template {
1056+ let (template, needs_listeners) =
1057+ get_or_create_template(cached_set, change_list, registry, cached_roots, template_id);
1058+ change_list.replace_with();
1059+
1060+ let mut old_forcing = None;
1061+ if needs_listeners {
1062+ old_forcing = Some(change_list.push_force_new_listeners());
9311063 }
1064+
1065+ diff(
1066+ cached_set,
1067+ change_list,
1068+ registry,
1069+ template,
1070+ new,
1071+ cached_roots,
1072+ );
1073+
1074+ if let Some(old) = old_forcing {
1075+ change_list.pop_force_new_listeners(old);
1076+ }
1077+
1078+ change_list.commit_traversal();
1079+ } else {
1080+ create(cached_set, change_list, registry, new, cached_roots);
1081+ change_list.replace_with();
9321082 }
1083+ registry.remove_subtree(old);
1084+}
1085+
1086+fn create_with_template(
1087+ cached_set: &CachedSet,
1088+ change_list: &mut ChangeListBuilder,
1089+ registry: &mut EventsRegistry,
1090+ template_id: CacheId,
1091+ node: &Node,
1092+ cached_roots: &mut FxHashSet<CacheId>,
1093+) {
1094+ debug_assert!(change_list.traversal_is_committed());
1095+
1096+ // [...]
1097+ let (template, needs_listeners) =
1098+ get_or_create_template(cached_set, change_list, registry, cached_roots, template_id);
1099+ // [... template]
1100+
1101+ // Now diff the node with its template.
1102+ //
1103+ // We must force adding new listeners instead of updating existing ones,
1104+ // since listeners don't get cloned in `cloneNode`.
1105+ let mut old_forcing = None;
1106+ if needs_listeners {
1107+ old_forcing = Some(change_list.push_force_new_listeners());
1108+ }
1109+
1110+ diff(
1111+ cached_set,
1112+ change_list,
1113+ registry,
1114+ template,
1115+ node,
1116+ cached_roots,
1117+ );
1118+
1119+ if let Some(old) = old_forcing {
1120+ change_list.pop_force_new_listeners(old);
1121+ }
1122+
1123+ // Make sure that we come back up to the level we were at originally.
1124+ change_list.commit_traversal();
9331125}