I experience the same issue but for me it startet with the 4x4.
Drone was out, with mods and loaded with stuff, I hit ne invisible wall with the 4x4. After that the drone was missing and I got the super speed for a bit. Looks like the super speed only starts at specific locations and stops at the same ones.
Yesterday I also experienced the extreme fps drop right after having the super speed. Also with the 4x4, but this time it happened at a specific location in the wasteland and it stopped after running back to the forest biome near my base.
I've also observed, that when working on my base, I still hear the sound effect of the drone dangling against some walls sometimes.