Distance search performance

Hey,
Thanks for this awesome plugin :).
i have the issue when the list become too big e.g. > 100 and im trying to enhance the performance of it:

```
function sortByDistanceDesc(dimensions, pointer, lastPointer) {
pointer = [pointer.left, pointer.top]
lastPointer = lastPointer && [lastPointer.left, lastPointer.top]

var dim,
i = dimensions.length,
distances = []

while(i--){
dim = dimensions[i];
distances[i] = [i,d(dim,pointer), lastPointer && d(dim, lastPointer)];
}

distances = distances.sort(function (a,b) {
return b[1] - a[1] || b[2] - a[2] || b[0] - a[0]
})

// last entry is the closest
return distances
}
```

this function become costly while dragging the item because its called to calculate the nearest element in the list and its slow when the list is big, do you have any idea how to enhance it?