OK, so you are looking for ways to load your PHP website very fast. The easiest way is to use Gzip compression. This will compress contents from the server to users browser, which of course makes the file size small which is quick and easy to transmit in the bandwidth limited Internet connections.
To do this, you need to find the PHP template file that will be loaded first by your server, in most cases, this is index.php (common in most website platforms like WordPress).
Download this template to your Desktop and edit it, place the code below to your template file and then upload back to the server.
<?php
//This the top most code in your PHP template, for example the index.php
ob_start("ob_gzhandler");
//rest of your template code here
?>
You can verify if the gzip encoding has been activated after adding the gzip compression line ob_gzhandler. You can use this tool: http://www.gidnetwork.com/tools/gzip-test.php
To test successfully, you need to enter at least 3 URLs:
1.) One for your homepage
2.) Two URLs for inner page
This will ensure that gzip encoding is activated not only for the homepage but for the entire URLs in your website.
Other things that could make the website loading very fast is to compile PHP into a faster executing language, e.g C++. One of the best promising projects I have seen HipHop for PHP (http://developers.facebook.com/blog/post/358); which is developed and used by Facebook.
The good news is that they are releasing this to open source, so you can use it also. The concept is simple, the PHP is compiled into C++ and because this language eats a fewer server resources like memory and CPU usage, so in case can make your server efficient thus fast in loading web pages to your client browser.
Of course, you can use the traditional way for speeding up your website; and that is using caching. With caching, your server creates static pages in advance and then once there is a server request (coming from client browser for example), instead of executing PHP, your server will right away send the static HTML pages so there is no PHP execution in your server and your website loads fast.
Other obvious ways is to make your image as small as possible, aim for an image dimension of 400 x 400 pixels wide, and if ever use big images, compress it to a 10KB to 30Kb sizes; in this way you are decreasing all chances of making your website graphics heavy and in the end it will look friendly to your users.
Other details for improving your website loads fast is to use Google Page Speed, a Firefox extension which will be helpful in diagnosing website loading issues: http://www.devshed.com/c/a/PHP/Speed-up-Web-Page-Loading-Using-Google-Page-Speed/.
