Show user that a file loads in the background

Loading a 80MB XML file requires some time to process.
It would be nice to show the user that it's being loaded in the background by e.g. dimming the view and perhaps showing a waiting cursor.
One could say that if a load process needs more than one second to finish, the view should signalize it's background activity in some way.

PS When loading such a file it grows to about 160MB - TM had taken about 700MB. I'm very happy about this difference including background loading.