Currently Linux uses the same thread for the platform and render tasks, see fl_engine.cc:

  FlutterCustomTaskRunners custom_task_runners = {};
  custom_task_runners.struct_size = sizeof(FlutterCustomTaskRunners);
  custom_task_runners.platform_task_runner = &platform_task_runner;
  custom_task_runners.render_task_runner = &platform_task_runner;

Other platforms use separate threads. Consider doing this for Linux.

The side effect is FlutterCompositor.present_view_callback will be called from a different thead and require synchronization. There will also have to be careful management around resizing as the present may not be in the expected size.