diff --git a/UPGRADING b/UPGRADING
index 7a3aff95da8ef..858e1cffa9535 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -122,3 +122,6 @@ PHP 8.6 UPGRADE NOTES
 
 - JSON:
   . Improve performance of encoding arrays and objects.
+
+- Standard:
+  . Improved performance of array_fill_keys().
diff --git a/Zend/zend_hash.h b/Zend/zend_hash.h
index 57020bbcad0b2..3a501b7f37df1 100644
--- a/Zend/zend_hash.h
+++ b/Zend/zend_hash.h
@@ -473,6 +473,17 @@ static zend_always_inline bool zend_hash_str_exists_ind(const HashTable *ht, con
 			Z_TYPE_P(Z_INDIRECT_P(zv)) != IS_UNDEF);
 }
 
+static zend_always_inline zval *zend_symtable_add(HashTable *ht, zend_string *key, zval *pData)
+{
+	zend_ulong idx;
+
+	if (ZEND_HANDLE_NUMERIC(key, idx)) {
+		return zend_hash_index_add(ht, idx, pData);
+	} else {
+		return zend_hash_add(ht, key, pData);
+	}
+}
+
 static zend_always_inline zval *zend_symtable_add_new(HashTable *ht, zend_string *key, zval *pData)
 {
 	zend_ulong idx;
diff --git a/ext/standard/array.c b/ext/standard/array.c
index 4097d71899011..32d28fe70220a 100644
--- a/ext/standard/array.c
+++ b/ext/standard/array.c
@@ -2830,16 +2830,19 @@ PHP_FUNCTION(array_fill_keys)
 
 	ZEND_HASH_FOREACH_VAL(Z_ARRVAL_P(keys), entry) {
 		ZVAL_DEREF(entry);
-		Z_TRY_ADDREF_P(val);
 		if (Z_TYPE_P(entry) == IS_LONG) {
-			zend_hash_index_update(Z_ARRVAL_P(return_value), Z_LVAL_P(entry), val);
+			zend_hash_index_add(Z_ARRVAL_P(return_value), Z_LVAL_P(entry), val);
 		} else {
 			zend_string *tmp_key;
 			zend_string *key = zval_get_tmp_string(entry, &tmp_key);
-			zend_symtable_update(Z_ARRVAL_P(return_value), key, val);
+			zend_symtable_add(Z_ARRVAL_P(return_value), key, val);
 			zend_tmp_string_release(tmp_key);
 		}
 	} ZEND_HASH_FOREACH_END();
+
+	if (Z_REFCOUNTED_P(val)) {
+		GC_ADDREF_EX(Z_COUNTED_P(val), zend_hash_num_elements(Z_ARRVAL_P(return_value)));
+	}
 }
 /* }}} */