Is 60FPS to be considered only during Web animations?

I am going through tutorials and articles on how to achieve 60FPS for web animations. I am working on the web performance on a site and was wondering whether 60FPS is valid on the idle page too?

Eg:- While scrolling page I see theres some drop on the frame rate due to some long running script which was triggered on scroll events.

I might sound too noob here, but wanted to understand from others where all the 60FPS is expected.

So I wanted to understand more whether a good performing site should always achieve 60FPS even on idle state too?

I googled around and mostly found 60FPS was measured for Web Animations only.