For as long as High Score has existed on this leaderboard, there has been a description for Vert Slowdowns while submitting runs. Evidently, this isn't clear enough, so a similar description is now in the category rules.

Verts are the vertically moving obstacles, the ones that move up and down. They stay still for a while when they're first loaded in. Usually this time is short enough that you don't notice, but if you're going quick enough you can reach them and touch them before they begin moving, and they won't kill you. That's what a vert slowdown is.

They're super powerful since they bring you to a complete stop. The current world record uses one three times. 4:08, 5:06, and 5:22 are the times.

First high score run, so I guess this sets the precedent. High Score runs will use milliseconds to show the score.