I remember the problem. It’s the slow parts take make the animation feel/look jagged. I would test around and make your own Bézier Curve Timings. It takes time and practice, Faruk. Also try to make an elastic effect on the middle start/middle/end. It could erase the stuttering also.
I’ve added one. It is similar to the standard one. But just a tad difference. Seems to slide better on Chrome.
You can also look on the Internet and see what other are using for curves. A good start is at our friends at Greensock.
Here is your index.html with the Smooth Bézier Curve.
index_smooth.zip (428.7 KB)
Small Question: are you going to set these Widgets to Overflow? It’s weird to see these scrollbars.