How can PHP developers ensure that their code is optimized for performance when handling dynamic user interactions on a web page?

PHP developers can optimize their code for performance when handling dynamic user interactions on a web page by minimizing database queries, utilizing caching mechanisms, and optimizing code logic. One way to achieve this is by using prepared statements to prevent SQL injection attacks and improve database query performance.

// Example of using prepared statements to optimize database queries
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username");
$stmt->bindParam(':username', $username, PDO::PARAM_STR);
$stmt->execute();
$user = $stmt->fetch();