diff --git a/UPGRADING b/UPGRADING
index ddef86c1ae37..5da76d924fbf 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -128,3 +128,4 @@ PHP 8.6 UPGRADE NOTES
   . Improved performance of array_unshift().
   . Improved performance of array_walk().
   . Improved performance of intval('+0b...', 2) and intval('0b...', 2).
+  . Improved performance of str_split().
diff --git a/ext/standard/string.c b/ext/standard/string.c
index 6fb39c5a6bd2..ddf4221bf6ed 100644
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -6152,23 +6152,31 @@ PHP_FUNCTION(str_split)
 		}
 
 		array_init_size(return_value, 1);
-		add_next_index_stringl(return_value, ZSTR_VAL(str), ZSTR_LEN(str));
+		GC_TRY_ADDREF(str);
+		add_next_index_str(return_value, str);
 		return;
 	}
 
 	array_init_size(return_value, (uint32_t)(((ZSTR_LEN(str) - 1) / split_length) + 1));
+	zend_hash_real_init_packed(Z_ARRVAL_P(return_value));
 
 	n_reg_segments = ZSTR_LEN(str) / split_length;
 	p = ZSTR_VAL(str);
 
-	while (n_reg_segments-- > 0) {
-		add_next_index_stringl(return_value, p, split_length);
-		p += split_length;
-	}
+	ZEND_HASH_FILL_PACKED(Z_ARRVAL_P(return_value)) {
+		zval zv;
+		while (n_reg_segments-- > 0) {
+			ZEND_ASSERT(split_length > 0);
+			ZVAL_STRINGL_FAST(&zv, p, split_length);
+			ZEND_HASH_FILL_ADD(&zv);
+			p += split_length;
+		}
 
-	if (p != (ZSTR_VAL(str) + ZSTR_LEN(str))) {
-		add_next_index_stringl(return_value, p, (ZSTR_VAL(str) + ZSTR_LEN(str) - p));
-	}
+		if (p != (ZSTR_VAL(str) + ZSTR_LEN(str))) {
+			ZVAL_STRINGL_FAST(&zv, p, (ZSTR_VAL(str) + ZSTR_LEN(str) - p));
+			ZEND_HASH_FILL_ADD(&zv);
+		}
+	} ZEND_HASH_FILL_END();
 }
 /* }}} */