Chceckbox :checked animation is laggy only for the first time

I want to create pure CSS, animated checkbox. everything is fine except the moment when I load the page with my checkbox and it has pseudoclass :checked. When I uncheck it for the first time, the animation (BounceIn) is laggy.

I tried using transition, but the effect is the same.

https://codepen.io/piokrako/pen/rELvdd?editors=1100

.checkbox:not(.checkbox--disabled) input[type="checkbox"]:focus:checked + .input__row .checkbox__field { animation: elementBounceIn .6s ease 0ms 1 forwards; }