How can functions in PHP scripts be optimized for better performance and readability?

To optimize functions in PHP scripts for better performance and readability, it is important to follow best practices such as avoiding nested loops, minimizing global variables, using efficient algorithms, and breaking down complex functions into smaller, more manageable ones. Additionally, using built-in PHP functions and libraries can help improve performance and readability.

// Example of optimizing a function for better performance and readability

// Original function
function calculateSum($arr) {
    $sum = 0;
    foreach ($arr as $num) {
        $sum += $num;
    }
    return $sum;
}

// Optimized function
function calculateSumOptimized($arr) {
    return array_sum($arr);
}