diff --git a/lib/core/utils/dq-element.js b/lib/core/utils/dq-element.js
index 47bcc64e..93498e91 100644
--- a/lib/core/utils/dq-element.js
+++ b/lib/core/utils/dq-element.js
@@ -18,6 +18,154 @@ function truncate(str, maxLength) {
   return str;
 }
 
+/**
+ * Escapes a string for use in CSS selectors
+ * @param {String} str - The string to escape
+ * @returns {String} The escaped string
+ */
+function escapeCSSSelector(str) {
+  // Use the CSS.escape method if available
+  if (window.CSS && window.CSS.escape) {
+    return window.CSS.escape(str);
+  }
+  // Simple fallback for browsers that don't support CSS.escape
+  return str
+    .replace(/[!"#$%&'()*+,./:;<=>?@[\\\]^`{|}~]/g, '\\$&')
+    .replace(/^\d/, '\\3$& ');
+}
+function generateSelectorWithShadow(elm) {
+  const selectors = getShadowSelector(elm);
+  if (typeof selectors === 'string') {
+    return selectors;
+  } else {
+    // merge selectors of an array with ,
+    return selectors.join(',').replace(/,$/, '');
+  }
+}
+
+function getShadowSelector(elm) {
+  if (!elm) {
+    return '';
+  }
+  let doc = (elm.getRootNode && elm.getRootNode()) || document;
+  // Not a DOCUMENT_FRAGMENT - shadow DOM
+  if (doc.nodeType !== 11) {
+    return getFullPathSelector(elm);
+  }
+
+  const stack = [];
+  while (doc.nodeType === 11) {
+    if (!doc.host) {
+      return '';
+    }
+    stack.unshift({ elm, doc });
+    elm = doc.host;
+    doc = elm.getRootNode();
+  }
+
+  stack.unshift({ elm, doc });
+  return stack.map(item => getFullPathSelector(item.elm));
+}
+
+function getFullPathSelector(elm) {
+  if (elm.nodeName === 'HTML' || elm.nodeName === 'BODY') {
+    return elm.nodeName.toLowerCase();
+  }
+
+  if (cache.get('getFullPathSelector') === undefined) {
+    cache.set('getFullPathSelector', new WeakMap());
+  }
+
+  // Check cache first
+  const sourceCache = cache.get('getFullPathSelector');
+  if (sourceCache.has(elm)) {
+    return sourceCache.get(elm);
+  }
+
+  const element = elm;
+  const names = [];
+  while (elm.parentElement && elm.nodeName !== 'BODY') {
+    if (sourceCache.has(elm)) {
+      names.unshift(sourceCache.get(elm));
+      break;
+    } else if (elm.id) {
+      // Check if the ID is unique in the document before using it
+      const escapedId = escapeCSSSelector(elm.getAttribute('id'));
+      const elementsWithSameId = document.querySelectorAll(`#${escapedId}`);
+      if (elementsWithSameId.length === 1) {
+        // ID is unique, safe to use
+        names.unshift('#' + escapedId);
+        break;
+      } else {
+        // ID is not unique, fallback to position-based selector
+        let c = 1;
+        let e = elm;
+        for (; e.previousElementSibling; e = e.previousElementSibling, c++) {
+          // Increment counter for each previous sibling
+        }
+        names.unshift(`${elm.nodeName.toLowerCase()}:nth-child(${c})`);
+      }
+    } else {
+      let c = 1;
+      let e = elm;
+      for (; e.previousElementSibling; e = e.previousElementSibling, c++) {
+        // Increment counter for each previous sibling
+      }
+      names.unshift(`${elm.nodeName.toLowerCase()}:nth-child(${c})`);
+    }
+    elm = elm.parentElement;
+  }
+
+  const selector = names.join('>');
+  sourceCache.set(element, selector);
+  return selector;
+}
+
+function getSourceOpt(element) {
+  if (!element) {
+    return '';
+  }
+
+  // Initialize cache if needed
+  if (cache.get('getSourceEfficient') === undefined) {
+    cache.set('getSourceEfficient', new WeakMap());
+  }
+
+  // Check cache first
+  const sourceCache = cache.get('getSourceEfficient');
+  if (sourceCache.has(element)) {
+    return sourceCache.get(element);
+  }
+
+  // Compute value if not cached
+  const tagName = element.nodeName?.toLowerCase();
+  if (!tagName) {
+    return '';
+  }
+
+  let result;
+  try {
+    const attributes = Array.from(element.attributes || [])
+      .filter(attr => !attr.name.startsWith('data-percy-'))
+      .map(attr => `${attr.name}="${attr.value}"`)
+      .join(' ');
+    const closingTag = element.children.length ? false : true;
+    if (closingTag) {
+      result = `<${tagName} ${attributes}>${element.textContent}</${tagName}>`;
+    } else {
+      result = attributes ? `<${tagName} ${attributes}>` : `<${tagName}>`;
+    }
+    result = truncate(result, 300); // Truncate to 300 characters
+    // Store in cache
+    sourceCache.set(element, result);
+  } catch (e) {
+    // Handle potential errors (like accessing attributes on non-element nodes)
+    result = `<${tagName || 'unknown'}>`;
+  }
+
+  return result;
+}
+
 function getSource(element) {
   if (!element?.outerHTML) {
     return '';
@@ -84,7 +232,11 @@ function DqElement(elm, options = null, spec = {}) {
   this.source = null;
   // TODO: es-modules_audit
   if (!axe._audit.noHtml) {
-    this.source = this.spec.source ?? getSource(this._element);
+    if (axe._cache.get('runTypeAOpt')) {
+      this.source = this.spec.source ?? getSourceOpt(this._element);
+    } else {
+      this.source = this.spec.source ?? getSource(this._element);
+    }
   }
 }
 
@@ -94,6 +246,9 @@ DqElement.prototype = {
    * @return {String}
    */
   get selector() {
+    if (axe._cache.get('runTypeAOpt')) {
+      return this.spec.selector || [generateSelectorWithShadow(this.element)];
+    }
     return this.spec.selector || [getSelector(this.element, this._options)];
   },