title: What is the ideal target time for rendering a page of a PHP forum?
body: <p>I am creating this question because I am currently working on my free time (for fun) on a PHP forum, using MySQL for my database. And for a little while now (most of the essential features being implemented), I have been questioning the performance of my scripts.</p>
  
  <p>I already did some profiling of my scripts and improved some of them, but I eventually always end up with the same question: <strong>what is a good target time to render the typical page of a forum ?</strong> In my case, such a page consists in displaying 20 to 50 messages of a given topic (users can decide how many messages per page they want to display) with roughly half of them using features like uploads displayed as a gallery below a message (which involves string parsing and checking the existence of a file with file_exists()).</p>
  
  <p>After reading some topics on performance with PHP on this website, I learned, among others, that Youtube had a target render time of 100ms (= 0,1s). I managed to have load times below this target time for my heaviest pages, but only after a while due to PHP caching with file_exists() (I run my project locally, with a WAMP Server). But I doubt I can really compare my project to a website as heavy in features as Youtube. So,</p>
  
  <ul>
  <li><p>When rendering (in HTML/CSS) my "typical" page, what time should I target ? Is it acceptable to stick to the 100ms limit, or should I go way below (for example, below 50ms) ? Are there any known statistics about current state-of-the-art forums I could use for reference ?</p></li>
  <li><p>Since I am currently working with WAMP Server, does it introduce bias while profiling my scripts ? Is it equivalent to your average PHP-enabled HTTP server, or does it run slower/faster on average ?</p></li>
  </ul>
  
  <p>This question interests me a lot, as some features I designed add some overhead to my scripts (which scales with the amount of messages being displayed). For example, my format code to embed videos is not parsed at the creation of a message, but at its display, as I want to be able to easily change the embed code as well as allowing users to choose how videos are embedded (directly, or with small/HQ thumbnail which is replaced with the embed code upon clicking) for their comfort. Of course, I could as well parse the code at the submission of a new message to reduce the overhead, but I want to be sure this is necessary.</p>
  
  <p>I hope this is not too vague... thank you in advance for your answers.</p>