As has been noted in the comments, efficiency is the least of your concerns here, readability and thereby maintainability are more important. Typically you'd use a fail early approach to achieve this:
function myTest($a, $b, $c) {
if ($a == $b) {
return false;
}
if ($c < 10) {
return false;
}
if (...) {
return false;
}
...
return true;
}
Alternatively you may want to be throwing specific exceptions or return specific error codes instead of merely returning false
to signal exactly what was wrong.