It looks like you're looking for a — likely a mod or enhanced version of Friday Night Funkin' using the popular Psych Engine.
: Customize visual smoothness and cap FPS for better stability. fnf psych engine 063 pc extra quality
The list of songs populated instantly. No lag. No micro-stutter. It was liquid. He scrolled down to "Tutorial," just to see if the game would crash on the simplest beatmap. He selected it. It looks like you're looking for a —
Forget external tools. In 0.6.3, you can pause any song, open the editor, and start placing notes. Features include: No lag
He reached for the power plug, but his hand stopped mid-air. He felt a rhythmic pulse in his own chest, perfectly synced to the 180 BPM of the song. He wasn't playing the game anymore. The engine was playing him.