I suppose you aren't familiar with Tetris: The Grand Master. That really is how fast the blocks are falling at the highest level.

It starts off slow, but instead of the level going up every 10 lines like in the original game, the level (max 999) goes up every time you drop a piece and every time you clear a line, with the exception of each time you go the next hundreds digit, which is entirely based on lines cleared. After level 500, there is no airborne phase of the blocks; they instantly appear at the bottom.

Here's a playthrough of someone playing the first game in the series.
Part 1 (levels 1-513)
Part 2 (levels 493-Complete