Are you testing a final published build or in edotor?
If in editor the grass maps are probably re-computing.
Overall, its not normal behaviour to zip from one place to another and not have to load.
If you are doing so for a transition shot or cinemeatic, just add foliage as meshes that are set to never be culled.
If you are not, you will always have some kind of loadong when zipping to different areas.
Its not as bad if the grass maps exist.