Why only on iOS devices is the picture dragged and the scroll lags?

Question

css

sdelaymne.website

Faced a problem on my own site because of the image and scrolling. No matter what ios devices and browsers I open from, my large photo is super-stretched in height, and on the contrary, it shrinks in width. Also, the scroll seems to lag, and the scrolling animation is too abrupt and slow - the "inertia" of the scroll disappears.

I thought that it was the Retina display, they say it upscales pictures for beauty, but I couldn’t find a solution (

UPD: The issue with the scroll is resolved) There was only a question with the picture)

I interviewed everyone who knows at least something about layout, Habr, help!