php - Opening/closing tags & performance?

Question

This may be a silly question, but as someone relatively new to PHP, I'm wondering if there are any performance-related issues to frequently opening and closing PHP tags in HTML template code, and if so, what might be best practices in terms of working with PHP tags?

My question is not about the importance/correctness of closing tags, or about which type of code is more readable than another, but rather about how the document gets parsed/executed and what impact it might have on performance.

To illustrate, consider the following two extremes:

Mixing PHP and HTML tags:

<?php echo
   '<tr>
       <td>'.$variable1.'</td>
       <td>'.$variable2.'</td>
       <td>'.$variable3.'</td>
       <td>'.$variable4.'</td>
       <td>'.$variable5.'</td>
   </tr>'
?>
// PHP tag opened once

Separating PHP and HTML tags:

<tr>
   <td><?php echo $variable1 ?></td>
   <td><?php echo $variable2 ?></td>
   <td><?php echo $variable3 ?></td>
   <td><?php echo $variable4 ?></td>
   <td><?php echo $variable5 ?></td>
</tr>
// PHP tag opened five times

Would be interested in hearing some views on this, even if it's just to hear that it makes no difference.

Thanks.

Answer 1

3 simple rules for you to get it right:

• No syntax issue can affect performance. Data manipulation does.
• Speak of performance only backed with results of profiling.
• Premature optimization is the root of all evil

Performance issues are quite hard to understand. It is advised for the newbies not to take it into account. Because they are always impressed with trifle things and fail to see a real important things. Just because lack of experience.

Same for your question. Imagine you'll ever get some difference. Even big one, say, one method is 2 times faster. Oh my, 2 times! I choose it and optimized my app well, it will run 50% faster now!

Wrong. Not 50%. You'd never notice or even measure this speed increase. Because you optimized a part that take only 0,0001% of whole script runtime.

As for the big HTML tables, it take a long time for the browser to render it. Much more than you took to generate.

Profiling is a key word in the performance world. One can trash any performance related question with no doubts if there is no word "profiling" in it. At the same time profiling is not a rocket science. It's just measuring of runtime of different parts of your script. Can be done with some profiler, like xdebug, or even manually, using microtime(1). And only after detecting the slowest part, may you start with tests.

Learn to profile before asking performance questions. And learn not to ask performance questions if there is no real reasons for it.

Premature optimization is the root of all evil - D.Knuth.