Pausing: There are timers that only "tick" every 64 frames, including car spawn timers and the time remaining. Bypass this "tick" by pausing at the right time. Useful for delaying appearance of cars. Each pause costs 4 frames, plus 2 more in the finish countdown if it saved a timer tick, but proper manipulation of other cars can potentially make up for that.
Bumping cars: There are seven ways to interact with other cars. I sometimes bump into the back of one straight on to improve its speed, as the follow-up curve is nasty and I really want a car "on rails" to bounce off of, and for it to keep up with me rather than me slowing down for it. The other six ways have you fly off to some side, but the back-left and back-right collisions slow you down and potentially slowing the other car as well, but are easier to cause at frame-precise times.
Car distance: There is a number for how far along the lane the car is, and another one for "sub-pixel" (x/64) value of that. This "sub-pixel" goes up by the difference in speed, regardless of who is faster. One can build it up at a higher speed, then slow down just below the other car's speed to reach the 64 threshold and get them one "notch" further ahead at minimal distance loss yourself.
Saturn may have made frame-perfect cornering, but manipulating traffic is where the real savings are. This requires some interesting maneuvering and a good memory watch script.
Times measured by 2-byte value at address 0x0029, when it freezes at the next course preview:
Course 1: 9393 frames (Saturn: 9827)
Course 2: 9305 frames (Saturn: 10559)
Course 1: 9393 frames (Saturn: 9827)
Course 2: 9305 frames (Saturn: 10559)
Seems each course is very well "packaged" away from other courses. Even sub-speed values are reset upon entry. Might be possible for sync stability for swapping in another movie's input for various courses. Maybe.