Iterating using AssetDatabase.EnumerateAssets(filter) can be really costly.
{code:java}
var it = AssetDatabase.EnumerateAllAssets(filter);
while (it.MoveNext())
{
    var current = it.Current;
    if (current == null)
    {
        Debug.Log($"null");
    }
    else
    {
        Debug.Log($"Match: {current.name}");
    }
}

{code}
In the above example, MoveNext will return only if a result is found OR if all assets have been iterated on. In big project this leads to big slowdown.

Note that this behavior is also seen in the Project browser. 

Ideally we would like an iterator that allows to iterate over all assets and that allows to Filter manually. Or that returns a "dummy" invalid Current for each asset that doesn't fulfill the Filter.