Is there any larger goal in doing this? Particularly, I'd anticipate this might impose a small performance cost on loading objects, which we do super frequently.

I started writing a unit test whi h involved loading all classes, excluding interfaces. I ended up abandoning it.

Let me clarify whether or not this suffers from a performance penalty.

Running the following code in rP:

<?php

require_once __DIR__.'/scripts/__init_script__.php';

$start_time = microtime(true);

for ($i = 0; $i < 10000; $i++) {
  id(new PhutilSymbolLoader())
    ->setAncestorClass('LiskDAO')
    ->loadObjects();
}

$end_time = microtime(true);

echo pht('Completed in %f seconds.', $end_time - $start_time)."\n";

The results are as follows:

So, on average, this method is 1.2% slower.