perf: Avoid hashtable rebuilding on small hashmaps

Signed-off-by: Dmitry Dygalo <dmitry@dygalo.dev>

Author: Stranger6667

CHANGELOG.md

@@ -11,6 +11,7 @@
 - Avoid unnecessary check for double quotes.
 - Avoid creating an unnecessary string cache entry.
 - Use a more precise estimate for the size of the number of applied styles.
+- Avoid hashtable rebuilding on small hashmaps.
 
 ## [0.16.0] - 2025-07-16
 

bindings/c/CHANGELOG.md

@@ -11,6 +11,7 @@
 - Avoid unnecessary check for double quotes.
 - Avoid creating an unnecessary string cache entry.
 - Use a more precise estimate for the size of the number of applied styles.
+- Avoid hashtable rebuilding on small hashmaps.
 
 ## [0.16.0] - 2025-07-16
 

bindings/java/CHANGELOG.md

@@ -11,6 +11,7 @@
 - Avoid unnecessary check for double quotes.
 - Avoid creating an unnecessary string cache entry.
 - Use a more precise estimate for the size of the number of applied styles.
+- Avoid hashtable rebuilding on small hashmaps.
 
 ## [0.16.0] - 2025-07-16
 

bindings/javascript/CHANGELOG.md

@@ -11,6 +11,7 @@
 - Avoid unnecessary check for double quotes.
 - Avoid creating an unnecessary string cache entry.
 - Use a more precise estimate for the size of the number of applied styles.
+- Avoid hashtable rebuilding on small hashmaps.
 
 ## [0.16.0] - 2025-07-16
 

bindings/python/CHANGELOG.md

@@ -11,6 +11,7 @@
 - Avoid unnecessary check for double quotes.
 - Avoid creating an unnecessary string cache entry.
 - Use a more precise estimate for the size of the number of applied styles.
+- Avoid hashtable rebuilding on small hashmaps.
 
 ## [0.16.0] - 2025-07-16
 

bindings/ruby/CHANGELOG.md

@@ -11,6 +11,7 @@
 - Avoid unnecessary check for double quotes.
 - Avoid creating an unnecessary string cache entry.
 - Use a more precise estimate for the size of the number of applied styles.
+- Avoid hashtable rebuilding on small hashmaps.
 
 ## [0.16.0] - 2025-07-16
 

css-inline/src/html/serializer.rs

@@ -248,7 +248,11 @@ impl<'a, W: Write> HtmlSerializer<'a, W> {
 
         let mut styles = if let Some(node_id) = style_node_id {
             self.styles.swap_remove(&node_id).map(|mut styles| {
-                styles.sort_unstable_by(|_, (a, _), _, (b, _)| a.cmp(b));
+                // Even though, there is a fast path for sorting of <2 elements, `indexmap` still
+                // rebuilds the hashtable unnecessarily
+                if styles.len() > 1 {
+                    styles.sort_unstable_by(|_, (a, _), _, (b, _)| a.cmp(b));
+                }
                 styles
             })
         } else {