rqt_bag slow to respond after ceasing to record on Windows

[sloretz]

Using a recent ROS Rolling packaging job, rqt_bag makes rqt slow and unresponsive after ceasing to record.

Start a launch file with data to record

ros2 launch dummy_robot_bringup dummy_robot_bringup.launch.py

Click the red record icon on rqt_bag

Select /joint_states for recording.

Wait a few seconds for it to record data (it's also slow to start).

Click the red record icon on rqt_bag again to stop recording.

The whole rqt window becomes very slow to repond. A good way to see this is to add rqt_plot and try to display /joint_states/position[0] - it will update very very slowly.