There are examples where at it may make things worse, sure. But in general if one browser is not able to understand how to layerize your page, there's a good chance other browsers will struggle as well.

Some operations are just fundamentally more difficult for any modern engine to handles such as animated properties in a container that has group opacity or transparent layers with subpixel anti-aliases text.

A bit of careful tweaking can really improve the performance of a page. The problem is its a lot of domain specific knowledge.