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<?php $null = NULL; $empty = ''; $start=microtime(TRUE); for($i=0;$i<1000000000;$i++) { if($empty === '') { } } var_export(microtime(TRUE)-$start); echo "\n"; $start=microtime(TRUE); for($i=0;$i<1000000000;$i++) { if(!isset($null)) { } } var_export(microtime(TRUE)-$start); echo "\n";
Output for 5.3.7 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.7

Process exited with code 137.
preferences:
116.3 ms | 402 KiB | 114 Q