I can now explain, for me at least, the two main causes for my “phantom” slow downs. Which have gotten a little better in this latest version, but still extremely annoying.
There is one stretch of road that I take almost every day and night, so this eliminates the possibility that shadows are causing slow downs, however I never thought they did. Sometimes this road is bumper to bumper or I can be the only one around, both day and night. Two lane road, speed limit is 30mph, most of the time everyone including myself go 35mph. These two specific issues happen exactly the same... every time I drive this road to the point that I can predict each slow down the exact moment it will happen.
First thing FOR SURE causing slow downs are road lines disappearing, specifically the center yellow dashed line. These lines are worn out at specific patches for brief stretches and when FSD loses the center line it seems to immediately wants to slow down, but since the line eventually returns it speeds back up. The car will also start to track more to the center of the entire road as long as there is no oncoming traffic. I believe it's doing this because of FSD trying to drive more slowly in residential areas where there tends not to be a center line.
The second FOR SURE thing is the car immediately slowing down right at or just after the front tires drive over a pedestrian cross/walk pattern. It’s not a speed bump, since it doesn’t show up on the visualizations (as a speed bump does and the car slows before it), but it does have a similar look, minus the arrows. This occurs if people are around or not. These tend to be at most intersections with a stop light/sign, and obviously for all crosswalks.
Overall the car has been much better at being more assertive, especially at stops which greatly improves the overall feel. Though it does still slow down a bit too early most times, but at least it starts moving right away.
I hope they don't raise the price of the Subscription... I'd gladly lock in a multi-year price of $200... but that's about the limit for me...