diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8cfdccb..ebb9f041 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 ## Next
 
+
+- perf: Optimize mask widget rect collection to O(N) ([#269](https://github.com/PostHog/posthog-flutter/pull/269))
+
 # 5.12.0
 
 - feat: flutter error tracking support for web ([#243](https://github.com/PostHog/posthog-flutter/pull/243))
diff --git a/lib/src/replay/element_parsers/element_data.dart b/lib/src/replay/element_parsers/element_data.dart
index 4aeeb1fe..1d0fd023 100644
--- a/lib/src/replay/element_parsers/element_data.dart
+++ b/lib/src/replay/element_parsers/element_data.dart
@@ -22,9 +22,9 @@ class ElementData {
   }
 
   List<Rect> extractMaskWidgetRects() {
-    final rects = <Rect>[];
+    final rects = <Rect>{};
     _collectMaskWidgetRects(this, rects);
-    return rects;
+    return rects.toList();
   }
 
   List<ElementData> extractRects({bool isRoot = true}) {
@@ -47,14 +47,14 @@ class ElementData {
     return rects;
   }
 
-  void _collectMaskWidgetRects(ElementData element, List<Rect> rectList) {
-    if (!rectList.contains(element.rect)) {
+  void _collectMaskWidgetRects(ElementData element, Set<Rect> rectSet) {
+    if (!rectSet.contains(element.rect)) {
       if (element.widget is PostHogMaskWidget) {
-        rectList.add(element.rect);
+        rectSet.add(element.rect);
       } else if (element.widget is TextField) {
         final textField = element.widget as TextField;
         if (textField.obscureText) {
-          rectList.add(element.rect);
+          rectSet.add(element.rect);
         }
       }
     }
@@ -62,7 +62,7 @@ class ElementData {
     final children = element.children;
     if (children != null && children.isNotEmpty) {
       for (var child in children) {
-        _collectMaskWidgetRects(child, rectList);
+        _collectMaskWidgetRects(child, rectSet);
       }
     }
   }