iris: eliminate retained-frame heap churn

core/src/primitive/text.rs

@@ -617,6 +617,15 @@ impl From<&TextAttrs> for TextShapeAttrs {
     }
 }
 
+impl TextShapeAttrs {
+    fn matches(&self, attrs: &TextAttrs) -> bool {
+        self.color == attrs.color
+            && self.font_size == attrs.font_size
+            && self.line_height == attrs.line_height
+            && self.family == attrs.family
+    }
+}
+
 pub const LINE_HEIGHT_MULT: f32 = 1.1;
 
 impl Default for TextAttrs {
@@ -701,10 +710,16 @@ impl TextBuffer {
         width: Option<f32>,
         density: f32,
     ) {
-        let shape_attrs = TextShapeAttrs::from(attrs);
-        if self.shaped.as_ref() == Some(&(shape_attrs.clone(), width, density)) {
+        if self
+            .shaped
+            .as_ref()
+            .is_some_and(|(old, old_width, old_density)| {
+                old.matches(attrs) && *old_width == width && *old_density == density
+            })
+        {
             return;
         }
+        let shape_attrs = TextShapeAttrs::from(attrs);
         let base_family = data.resolve_family(&attrs.family);
         let span_families: Vec<Option<String>> = self
             .spans