benchmark: boolean variables value check

$a = NULL;

$t = microtime(true);
for(
$i = 0; $i<10000000; $i++) {
if (
$a) {} }
print
microtime(true)-$t.“n”; //2.84 sec

$t = microtime(true);
for(
$i = 0; $i<10000000; $i++) {
if (
$a==true) {} }
print
microtime(true)-$t.“n”; //3.52sec

$t = microtime(true);
for(
$i = 0; $i<10000000; $i++) {
if (
$a===true) {} }
print
microtime(true)-$t.“n”; //3.0 sec

$t = microtime(true);
for(
$i = 0; $i<10000000; $i++) {
if (isset(
$a)) {} }
print
microtime(true)-$t; //3.08 sec