diff --git a/include/xy.h b/include/xy.h
index 60c2c886..5df03c79 100644
--- a/include/xy.h
+++ b/include/xy.h
@@ -36,9 +36,8 @@
 
 #include "types.h"
 
-/* Used to calculate an offset into an array.  Used for
-   dynamically sizing the world. */
-#define XYOFFSET(x, y) (((y) * WORLD_X) + (x))
+/* Fast version of sctoff() for normalized arguments: */
+#define XYOFFSET(x, y) (((y) * WORLD_X + (x)) / 2)
 
 #define XNORM(x) \
     (((x) < 0) ? ((WORLD_X - (-(x) % WORLD_X)) % WORLD_X) : ((x) % WORLD_X))
diff --git a/src/lib/update/finish.c b/src/lib/update/finish.c
index 5c2eb40c..a8464803 100644
--- a/src/lib/update/finish.c
+++ b/src/lib/update/finish.c
@@ -77,20 +77,15 @@ finish_sects(int etu)
     if (g_distptrs == NULL) {
 	logerror("First update since reboot, allocating buffer\n");
 	/* Allocate the information buffer */
-	g_distptrs = (struct distinfo *)(malloc((WORLD_X * WORLD_Y) *
-						sizeof(struct distinfo)));
+	g_distptrs = malloc((WORLD_X * WORLD_Y / 2) * sizeof(*g_distptrs));
 	if (g_distptrs == NULL) {
 	    logerror("malloc failed in finish_sects.\n");
 	    return;
 	}
-
-	logerror("Allocated '%lu' bytes '%d' indices\n",
-		 (unsigned long)(WORLD_X * WORLD_Y * sizeof(struct distinfo)),
-		 WORLD_X * WORLD_Y);
     }
 
     /* Wipe it clean */
-    memset(g_distptrs, 0, ((WORLD_X * WORLD_Y) * sizeof(struct distinfo)));
+    memset(g_distptrs, 0, (WORLD_X * WORLD_Y / 2) * sizeof(*g_distptrs));
 
     logerror("delivering...\n");
     /* Do deliveries */