[Cin] Optimizing playback

https://www.youtube.com/watch?v=A6DmHjZhXo0

From 2:20 to 4:05 I summarize briefly because it is in Italian. Compare "old" concept software (Kdenlive) that is heavy and limited in playback with "new" concept software (Olive). You can see that even if you add more effects and go back and forth, you don't notice the slowdown (also 2x reverse playback!). Can you find any optimization for CinGG by looking at its code?