See: https://flutter-flutter-perf.skia.org/e/?queries=sub_result%3Dworst_frame_build_time_millis%26sub_result%3Dworst_frame_rasterizer_time_millis%26test%3Dnew_gallery_ios__transition_perf&selected=commit%3D41923%26name%3D%252Carch%253Dintel%252Cbranch%253Dmaster%252Cconfig%253Ddefault%252Cdevice_type%253DiPhone_11%252Cdevice_version%253Dnone%252Chost_type%253Dmac%252Csub_result%253Dworst_frame_build_time_millis%252Ctest%253Dnew_gallery_ios__transition_perf%252C

Though UI time improves. Possibly due to UI getting better affinity/priority. Fix is to make raster task faster.