Delay Bug with infinite and centerMode

[reproduced here](https://codesandbox.io/s/81kkmr589j)

click the arrows a few times in the same direction. when the 'infinite' take place (the loop is ended), it takes time to the class 'slide-current' to be added to the center slide.

i've noticed that the delay is equal to the 'speed' option - with all slides its responsible for the animation delay, but from the last slide to the first of the next loop - its just delay with no animation.

i'de love to here if i'm doing something wrong, or if there's a better way to give the center slide a different look, with consistent transition.

thanks.