--- gcc/config/xm-i386sco.h	2018/04/24 17:55:21	1.1.1.1
+++ gcc/config/xm-i386sco.h	2018/04/24 18:00:20	1.1.1.2
@@ -5,3 +5,7 @@
 /* On SCO 3.2.1, ldexp rejects values outside [0.5, 1). */
 
 #define BROKEN_LDEXP
+
+/* Big buffers improve performance.  */
+
+#define IO_BUFFER_SIZE (0x8000 - 1024)