No need to protect red objects
The object in `GC_RED` does not need to be marked, and the objects connected to this object should also not need to be marked.
@@ -448,6 +448,7 @@ mrb_gc_destroy(mrb_state *mrb, mrb_gc *gc)
static void
gc_protect(mrb_state *mrb, mrb_gc *gc, struct RBasic *p)
{
+ if (is_red(p)) return;
#ifdef MRB_GC_FIXED_ARENA
if (gc->arena_idx >= MRB_GC_ARENA_SIZE) {
/* arena overflow error */
