Continous loop makes repositioning of slides visible in the background

When using the effect "concave"together with the option `continuous: true` the first iteration of slides looks good but the second iteration looks a bit different because during each transition you can see the last slide of the left side moving quickly to the right side in the background.

Is it possible to hide the fast moving, side-switching slide until the corresponding transition is almost over?

Reproduce the issue in the Bee3D slider using the "concave" effect with `continuous: true`, comparing the first and second slide iterations. Trace the transition and slide repositioning behavior; done means the fast side-switching slide is hidden until the transition is nearly complete and subsequent iterations match the first.

Written by the indexing model from the issue text.