Index: libtransmission/fdlimit.c
===================================================================
--- libtransmission/fdlimit.c	(revision 9401)
+++ libtransmission/fdlimit.c	(working copy)
@@ -356,6 +356,10 @@
         errno = err;
     }
 #endif
+#ifdef SYS_DARWIN
+        fcntl( file->fd, F_NOCACHE, 1 );
+        fcntl( file->fd, F_RDAHEAD, 1 );
+#endif
 
     return 0;
 }