Be it 80km/h or 50 km/h, you'll go pass 10m stretch of uneven road in less 1 sec or so. Not much different. Stock suspension might not able to react fast enough with the bumps. Most of the time you will find those area covered with small rocks and sands as well. I will brake slightly before going in. In case anything goes wrong, slower speed means more time for me to think and react.