Random Element node

I often use the Object Info node's Random output to add variation to the color/uv's/etc of objects like rooftiles or street pavement. However, this requires me separate these objects by loose parts, resulting in thousands of objects in my scene which seriously impact viewport performance (not to mention that the separation itself takes way too long). It would be extremely useful if I could get the same result without having to separate the individual tiles/bricks/.. Ideally there would be a node which basically does the same as the Random output but for separate "elements" or "loose parts" within an object.