Good find. I think that might be a physical limitation of how the ports are wired.
I know this may seem obvious but make sure the external display is using the same mode (resolution, color depth, refresh) as the internal panel and make sure they are mirrored (not extended). Having the display extended or at a higher resolution could negatively impact performance. Other than that I don't think there's a lot you can do, unfortunately.
A bus station is where a bus stops. A train station is where a train stops. On my desk, I have a work station…