first of all let me say congratulations for your great job, gsap definetly changed my career by now.
So... I made a codepen for you isolating one animation of our last website that do not render well on safari. Surprise! On codepen it works perfectly...
I'm still writing asking for help but I will understand if you can't or do not want, due to the website has another addons like scrollmagic etc etc.
I posted the codepen ( use it as reference on what we want ) and here goes the website: http://brand.uoc.edu.
As you can see on Safari absolutely all goes slow and jumping.