This is an area that has been a constant concern for me through several versions of the beta, and not because the car slows too aggresively. Quite the opposite.
My experience has been on two lane highways that enter a small village or town. The speed limit drops from 55 to 45 to 35 over a short distance, but the Tesla responds much too slowly to these changes. If I'm going 60 in a 55 zone, I may find myself still in the mid 50s when it changes to 35, and I may be a half mile down the road before the car reaches a speed where I would not be ticketed if clocked by police.
It would help a lot if the car would read and respond to the advance warnings (35 zone ahead), but it ignores them and changes its behavior only when the speed limit actually changes, and then it takes much too long to reach an acceptable speed.
I deal with it by dialing back the speed myself when I know what's coming, but even then the Tesla responds slowly to these changes.