Memory usage of long and short variable names

php_variable_name_memory_usage.php

<?php
class X
{
    private $_b;
    private $_e;
}
 
class Y
{
    private $_behaviors;
    private $_events;
}
 
$base = memory_get_usage();
 
echo "Start\n";
echo memory_get_usage() - $base."\n";
 
$a = new X();
$b = new X();
 
echo "X\n";
echo memory_get_usage() - $base."\n";
 
unset($a);
unset($b);
 
echo "Cleanup\n";
echo memory_get_usage() - $base."\n";
 
$a = new Y();
$b = new Y();
 
echo "Y\n";
echo memory_get_usage() - $base."\n";
 
unset($a);
unset($b);
 
echo "Cleanup\n";
echo memory_get_usage() - $base."\n";

You really need to create a number of objects of an order of magnitude to see the true difference. Two tiny classes aren't enough.