Set the 'BENCHMARK_FLG' to TRUE to do a benchmark.
Processing time can be obtained with the getProcessingTime method.
$object->getProcessingTime();
$op = new OnePlate();
$op->conf['BENCHMARK_FLG'] = TRUE;
$op->render("sample.tpl", $assign);
echo "Processing Time : " . $op->getProcessingTime();
Processing Time : 5.328 ms (non-cache)
Processing Time : 0.164 ms (cache)