Tween and going over keyframes lagging

I’ve had Toon boom 8.1 on my Mac OS for more than 2 years and I have never encountered this problem until I had updated it to version 10.13.6

  After i add audio, tweening and moving my drawing creates a choppy, laggy movement. There is a similar choppiness when i drag the red thing across the keyframes to look at them. No matter how long the audio is, it still lags the same amount as adding any other audio. Adding more/less layers does not effect the lag. When i remove the audio, tweeting and moving the red thing has no lag and works perfectly fine. The brush strokes, selecting tools/ect., playing the animation, audio sound, and everything else is all normal.

I checked the Mac requirements and I have all of them. I have a Wacom Intuos Cth-680 but I’ve unplugged it and plugged it back in and it had no effect on it whatsoever.

Please help, this problem has been occurring for 3 months and nothing has changed.