Why don't german cars exceed 155mph on downhill? Heck, why doesn't japanese JDM cars exceed 180/190 on downhill?
"Laggy" is a matter of perspective. There is a night and day difference in the way it goes from 140-150-160-170-180 VS 180-200.
Since you talked perspective, well my perspective is that M5 or E63 AMG go "swiftly" to 195 NOT Grandes and Civics.
Regarding Physics 101, there is a "reason" speed limiters are "electronic" because they cut the engine power in case of downhill to ensure speed limit.