We discussed speed-up video's, I just learned about this while learning reaper;
This is new so there isn't many video's, but I tried and its apply-able to sustaining notes too. Audio-stretch isn't something new, but it uses internal fade-in/outs and various algo's so they work best with drums or percussive sort of waves. I tried to fix an acoustic guitar arpeggio today and traditional stretch is very time consuming to get it right.
This worked really well and very fast, I think it manipulates the DAW playback speed without changing pitch (like super detailed metronome automation). So now not only people can play(back) super fast but will solo perfectly in time too