From 7989a2ff46e0dc8dc26b1571215768801fa04463 Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Fri, 17 Oct 2025 17:28:55 -0400
Subject: [PATCH] Preallocate capacity for id table in
 rb_singleton_class_clone_and_attach

We know the exact capacity for the constant table created in
rb_singleton_class_clone_and_attach so we can preallocate it.
---
 class.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/class.c b/class.c
index c8bf624140..77f2fba516 100644
--- a/class.c
+++ b/class.c
@@ -1193,7 +1193,7 @@ rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach)
         if (RCLASS_CONST_TBL(klass)) {
             struct clone_const_arg arg;
             struct rb_id_table *table;
-            arg.tbl = table = rb_id_table_create(0);
+            arg.tbl = table = rb_id_table_create(rb_id_table_size(RCLASS_CONST_TBL(klass)));
             arg.klass = clone;
             rb_id_table_foreach(RCLASS_CONST_TBL(klass), clone_const_i, &arg);
             RCLASS_SET_CONST_TBL(clone, table, false);