When reloading the page the animation change fps, what could be the reason?

There are two pages, such as index and about. The "about" page there's this animation: https://codesandbox.io/s/kwz622xvx7
The problem is the following: at the local version, if you go back to about page on the index, and then back to about the fps of the animation is reduced each time.
When I went to the about page -
Then switched to index -
Then returned to about -
Can't understand why this is happening. Project Vue