diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index 74d7ba2010a..4aefaf7fec6 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -62,7 +62,7 @@
  * may improve performance, but supplying a real spinlock implementation is
  * probably far better.
  */
-#define	NUM_SPINLOCK_SEMAPHORES		1024
+#define	NUM_SPINLOCK_SEMAPHORES		128
 
 /*
  * Define this if you want to allow the lo_import and lo_export SQL