Wind turbulence - either at shoulder height or straight onto the helmet - is tiring and distracting. One solution be to fit a different windscreen, but if you want to stick with the original, an additional spoiler can also be a solution.
These universal and easy to mount spoilers extend the original window by adding a little strip of extra material.
Because everyone has a different length and build and there are also many different bikes, most spoilers are adjustable in height and angle. This way you can create the most efficient - and least annoying - airflow for yourself.