How can I prevent loading images from stuttering?

I want to indicate that the page is loading, but even the loading animation stutters because many scripts are already running.

Can i write the code to prioritize Animation over other actions?

Please understand that I cannot show the actual code.
That ‘s too much .

All I can say is that I am using React.

I tried animation in CSS, gif and svg.
All of theses are stutters.