Suggestions for fast bulk comparison?

[salamanders]

I've generated and cached a chromaprint for 10k files.
Now I'd like to find duplicates.

My naive method is N^2:

prints.forEachIndexed { index, print ->
  val smallestNotSelf = prints.drop(index + 1).minByOrNull { chromaDistance(print, it) }
  // ... do stuff with smallestNotSelf...
}

fun chromaDistance(cl0: List<UInt>, cl1: List<UInt>): Double = cl0.zip(cl1).map { (c0, c1) ->
    (c0 xor c1).countOneBits()
}.average()

Is there a faster way to do all the comparisons?
Can I bail on a comparison if the first few ints are horribly different?
Do I have to compare everyone to everyone?
Maybe I can ditch anything with widely different lengths...