Outputting HTML in PHP, is there any upside to using ob_start or simply echo $html?

Question

Obviously there are usability and readability differences, but are there any advantages or disadvantages to the methods below – especially performance-wise?

function method1() {
  ob_start();
  ?><div>some html</div><?php
  echo ob_get_clean();
}

function method2() {
  ?><div>some html</div><?php
}

function method3() {
  echo '<div>some html</div>';
}

In particular between method1 and method2, does the added ob_start() cause a performance hit? Do I even need to use it when outputting HTML?

Answer 1

The "typical" use for ob_start() is to buffer the output so that you can still use functions like setcookie, header and others without having to worry about "did I output something already?", it'll work. Honestly I think that should be default behaviour but that's just me.

ob_start() gains real power when you give it a callback, however. I personally have this:

ob_start(function($html) {
    return preg_replace('/\r?\n\t*/','',$html);
});

This strips out newlines (and subsequent tabs) from the HTML source before sending it to the browser, thus minifying it.