Improving the speed of php

Question

I'm currently working on a website in PHP, and I'm wondering what the best practices/methods are to reduce the time requests take. I've build the site in a modular way, so a page would consist of a number of modules, and each of these would need to request information.

For example, I have a cart module, that (if a cart is set) will fetch the cart with the id (stored in a session variable) from the database and return its contents. I have another module that lists categories and this needs to fetch the categories from the database.

My system is built with models, and each model might also make a request, for example a category model will make a request to get products in that category.

For those interested, im running the application on Windows Server 2003 with IIS at the moment, but i am hoping to change to linux in the near future. I know this is a broad subject, im just curious about what to look out for and tool to use to help with the load., the answers so far have been very helpful.

Answer 1

Your high-level approach sounds reasonable, although it would be helpful to weigh such an approach against your actual code, data, and environment. That said:

A quick and easy way to make your code run even faster is to use a tool such as eAccelerator which will cache compiled PHP scripts. That way when a second request comes in the script does not have to be compiled a second time, which improves performance.

If you are developing a site with a large amount of users, you might consider caching data from the database, using a tool such as memcached.

Answer 2

The only practice/method to reduce the time requests take is called profiling.
First you determine the "bottleneck" - the most slow part of your application
Then speed up this very part of code.

Only that way.

Doing things "just in case" can make things worse.

The "Net" page in the Firebug console is good place to start.

Answer 3

Maybe you are looking for tips like these, you can google for this. An example here.

• require_once() is expensive
• Use echo’s multiple parameters instead of string concatenation.
• See if you can use strncasecmp, strpbrk and stripos instead of regex
• Error suppression with @ is very slow.
• $row[’id’] is 7 times faster than $row[id]

This is just general good practice but if your code is running slow - you need to profile your app and find out which areas are slow and address these accordingly.

Answer 4

require_once() is expensive

Use echo’s multiple parameters instead of string concatenation.

See if you can use strncasecmp, strpbrk and stripos instead of regex

Error suppression with @ is very slow.

$row[’id’] is 7 times faster than $row[id]

All these things are micro-optimization. It's not even worth looking at these until you've already done all the things that actually matter, like caching and reducing the number of unnecessary database queries. I would also recommend downloading Firebug and using the Page Speed tool, it can minify your CSS and optimize your images for you. PHP syntax is rarely large enough to worry about.

Edit: Although using @ is generally bad practice anyway. I've also never found the need to use require_once, __autoload seems to be much easier.