As you might notice, there are a plenty of note overloads in most parts. And as the speed increases, the notes stack into each other, making a more louder noise. The former preview had over 5k notes, while THIS ONE HAS OVER 35K NOTES.
For any of you wishing the FLP file, here you go.
http://www.mediafire.com/file/o6shtxsj7tdnykz/speedtest.flp