I've noticed this too, on my iPhone 6. It's not a device issue, it's a software issue. It's annoying but I don't mind it as long as it's not doing anything bad.

I just got an iPad mini 2 (my first iOS device) and want to use Chrome because of tab sync and other stuff. If you scroll down, the tab bar is hidden with an animation. Vice versa, if you scroll up it's shown, again with an animation. 

However, the animation lags horribly. As soon as the animation is done and the tab bar fully visible/hidden, everything is fine again. Since scrolling is an integral part of web browsing, using Chrome on the iPad feels worse than even on an old Android 4.1 budget smartphone. 

Is this normal or is my device defective? Can anything be done?

Chrome tab bar animation lag (iPad mini 2)