I think you are talking about the author environment, and I too experience major lag between selecting a layer, and the layer timeline and contents being displayed.
I would recommend sending this example to Articulate and reporting the performance issue to them. It appears to be caused by the number of elements on the layer. For example, if you have a layer with single item on it, for example a circle shape, and switch from a layer to this simple layer, the load time is much quicker. I think it's just extended processing time to draw everything to screen.
I've got a high performance PC and it takes a while on this machine, so I dread to think what it might be like for more common performance system to run this.
In a nutshell, no fix, but can confirm I experience the same issue due to the number of items on the layer (or maybe a single rogue item that features on each layer that has a problem?)