How can memory usage in PHP scripts be effectively measured and optimized for better performance?

Memory usage in PHP scripts can be effectively measured using functions like `memory_get_peak_usage()` and `memory_get_usage()`. To optimize memory usage for better performance, it's important to minimize unnecessary memory allocations, avoid loading large datasets into memory at once, and unset variables that are no longer needed.

// Measure memory usage
$initialMemory = memory_get_usage();

// Code logic that may consume memory

$finalMemory = memory_get_peak_usage();
$memoryUsed = $finalMemory - $initialMemory;
echo "Memory used: " . $memoryUsed . " bytes";