What are some common, straightforward ways to identify performance bottlenecks in a PHP application before attempting to optimize it?

Common approaches include using a profiling tool to measure exactly how much time is spent in different parts of your code, examining slow database query logs to identify expensive queries, enabling detailed application logging around suspected slow operations, and using browser developer tools to measure actual page load times from a user's perspective, all of which help you identify precisely where genuine performance problems exist rather than guessing and optimizing parts of the code that were never actually a meaningful bottleneck.

$start = microtime(true);
$result = expensiveOperation();
$duration = microtime(true) - $start;
error_log("Operation took $duration seconds");