Scroll further on x during demo drive test (#792)

diff --git a/test_driver/transitions_perf_test.dart b/test_driver/transitions_perf_test.dart
index bde9d1f..6d6f823 100644
--- a/test_driver/transitions_perf_test.dart
+++ b/test_driver/transitions_perf_test.dart
@@ -169,7 +169,7 @@
     await driver.scrollUntilVisible(
       demoList,
       demoItem,
-      dxScroll: -500,
+      dxScroll: -800,
       dyScroll: -50,
       alignment: 0.5,
       timeout: const Duration(seconds: 10),