diff --git a/.changeset/smooth-tigers-wink.md b/.changeset/smooth-tigers-wink.md
new file mode 100644
index 0000000000..74d09bc60c
--- /dev/null
+++ b/.changeset/smooth-tigers-wink.md
@@ -0,0 +1,5 @@
+---
+"stylelint": patch
+---
+
+Fixed: `selector-pseudo-element-no-unknown` performance
diff --git a/lib/rules/selector-pseudo-element-no-unknown/index.js b/lib/rules/selector-pseudo-element-no-unknown/index.js
index 1ba479919a..30a67571a5 100644
--- a/lib/rules/selector-pseudo-element-no-unknown/index.js
+++ b/lib/rules/selector-pseudo-element-no-unknown/index.js
@@ -42,10 +42,6 @@ const rule = (primary, secondaryOptions) => {
 		}
 
 		root.walkRules((ruleNode) => {
-			if (!isStandardSyntaxRule(ruleNode)) {
-				return;
-			}
-
 			const selector = ruleNode.selector;
 
 			// Return early before parse if no pseudos for performance
@@ -54,6 +50,10 @@ const rule = (primary, secondaryOptions) => {
 				return;
 			}
 
+			if (!isStandardSyntaxRule(ruleNode)) {
+				return;
+			}
+
 			parseSelector(selector, result, ruleNode, (selectorTree) => {
 				selectorTree.walkPseudos((pseudoNode) => {
 					const value = pseudoNode.value;