Hey @SWALKER ,
There are many things can cause that problem, and if in your Codepen works then the problem is probably somewhere in your site.
I saw that you have a css animation on your elements
.secondary a *, .site-footer a *, .site-header a *, a {
transition: all .2s linear;
}
Try to remove them, as they bring problems when you are also animating with GSAP.
If that doesn't fix the problem, try adding will-change: transform on your elements or force3D: true on your tween and see if this improves anything.