Level streaming - pre-caching not possible?

Hi,
is there any possibility of pre-loading levels? In my case I set a level change in a tunnel of a car driving simulation. You enter the tunnel from a winter landscape and exit the tunnel in a summer landscape. In the tunnel I placed a trigger volume which unloads the winter scene and loads the summer landscape. But I have always huge stuttering when this happens. This is really annoying. Both landscapes are really huge. Is it there a any possibility of a pre-load of a landscape so that that I get a smooth transition between the change? I am wondering that this is not possible. Also the option to switch only the visibility of the two levels leads to huge stuttering.

Best regards, Andreas