Debugging/Optimizing queries?

$c = $modx->newQuery('myClass');
$c->innerJoin('relatedClass','relatedAlias');
$c->where(array(
  'field' => 'value',
));
$c->sortby('sortfield','ASC');
$c->limit(10);
$objs = $modx->getCollection('myClass',$c);
echo $c->toSql();

<?php
$graph = '{"RelationAlias":{"AnotherRelationAlias":{}}}';

$c = $modx->newQuery('myClass');
$c->bindGraph($graph);

if ($debug) {
    $c->prepare();
    $modx->log(modX::LOG_LEVEL_ERROR, $c->toSQL(), 'HTML');
}
$objs = $modx->getCollectionGraph('myClass', $graph, $c);