But in your example the OS should be smart enough to realize "hey these pages related to the image viewer application aren't being messed with much in the last 12 hours, those should be high priority to swap out". So when they switch back to the image viewer app with the 100 gigapixel or whatever image they'll get that slowness hit but otherwise not experience it. Then the machine isn't constantly swapping, it just quietly hides those apps nobody is really touching.

The OS shouldn't be swapping hot pages when there's lots of things sitting around not doing much.