@stanislavstratil I see, maybe it's a matter of different settings in your Opera's profile, e.g. opera:flags#enable-lazy-frame-loading, or other flags and switches. As I said, it can be hidden at first on some pages, when the page is loaded, but when you move your mouse down, or closer to the right edge, it should show up.
Yep, using an extension seems to be a better solution, since it offers a bit of customization right away, and may provide you with the same "look and feel" in the future, without depending on the changes in the built-in feature.