MacOS High Sierra: Remove the lag when resizing a window quickly
That response looks entirely proper and the only thing I could see would be to have chrome somehow do less calculation of the content inside the frame and just resize the window and redraw / re-layout the text and content at a lower rate.

This seems like an intentional tradeoff - you can see the content is responding almost as fast as the mouse pointer. I'm not up on css / html enough to know if there's a hint you could embed to tell the web layout to not worry about layout changes so much and instead wait for you to pick a window size and then refresh.

My guess is the software isn't optimized for your use case at all. If chrome and safari and Firefox all work the same, you might simply see a decision to use CPU and cap frame rates due to energy consumption considerations and not for inherent limitations in the hardware. It could also be that all the responsiveness and resources are committed to making the content move inside the window so you know you are dragging and less about trying to track a window size change.

Dissecting this would make for an interesting research project or possibly a thesis for someone on software design tradeoffs and implementations. Which is a long way of saying, I don't think there's an easy solution for you to make a meaningful change other than use another browser or OS.