Speeding up WordPress from the backend

This is not a step-by-step tutorial and I don't have the promise that these will always work. They worked for me. Follow the links and the "more" links for detailed setup and step-by-step tutorials.

Cache in WordPress itself

Enable WordPress built-in object caching¹ in wp-config.php:

/* Cache */
define ( 'WP_CACHE', true );

This, on it's own is not a really big win, but depending on the theme & the plugins is can be a good addition. If you want a really powerful addition, install an Object Cache module along with a user object cache PHP module ( see below), for example APC Object Cache Backend² or APCu Object Cache Backend³, if you have APC or APCu⁴ installed. ( The second on is the user cache only version of APC intended to be used with the new OpCache⁵. )

PHP

opcode cache

Install an opcode cache plugin for PHP unless you're using PHP 5.5 which has Opcache built-in. For PHP 5.4, I'd recommend the opcache module as well, since APC is considered to be unstable for 5.4. Another choice could be Xcache⁶.

More:

• http://php.net/manual/en/book.opcache.php

Store PHP sessions in memcached

By default PHP is using the disk; putting session data into memcached can speed up PHP significantly⁷ and also solves loadbalancing issues. You'll need to install the memcache PHP extension and replace the original lines with these in php.ini:

session.save_handler = memcache
session.save_path = "tpc://127.0.0.1:11211"

More information:

• http://php.net/manual/en/memcached.sessions.php

Put PHP-FPM tmp directory to memory

Linux systems have tmpfs⁸ which is basically virtual filesystem in the memory - obviously faster than disk by magnitudes, but limited by the RAM.

If you have enough RAM, put the PHP-FPM temp directory into it ( add this to the pool configuration file, so this is per pool ):

php_admin_value[open_basedir] = /var/www/:/dev/shm/
php_admin_value[upload_tmp_dir] = /dev/shm/

More on SHM:

• http://www.cyberciti.biz/tips/what-is-devshm-and-its-practical-usage.html

nginx

Fire up file cache

nginx has built in open file cache ( caching descriptors, file headers, etc, but not the files themselves, that's either the job of the filesystem or Varnish⁹ )

Add this to nginx.conf:

##
# file cache
##
open_file_cache max=2048 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;

More information:

• http://wiki.nginx.org/HttpCoreModule#open_file_cache
• http://www.nginxtips.com/nginx-open-file-cache/

MySQL

###Add ( or add more ) query cache Enable query cache in my.cnf if you haven't done that already. While this is not always as useful as it seems, for WordPress, it can make a significant difference.

## QUERY CACHE ##
query_cache_type = 1
query_cache_limit = 1M
query_cache_size = 256M

More:

• http://www.cyberciti.biz/tips/enable-the-query-cache-in-mysql-to-improve-performance.html
• https://dev.mysql.com/doc/refman/5.6/en/server-system-variables.html#sysvar_query_cache_type

Use tmpfs as MySQL temporary folder (warning, this can be dangerous!)

In case you're extremely sure you have enough memory and the SHM segment is large enough ( see "Put PHP-FPM tmp directory to memory" above ) to handle the largest table's sorting, force MySQL to use the memory as temporary folder:

Change tmpdir in my.cnf to:

tmpdir = /dev/shm

More information & discussion:

• http://openquery.com.au/blog/experiment-mysql-tmpdir-on-tmpfs

These tips usually speed up WordPress even if you're not using a cache plugin - this is highly recommended though, even if all these tricks are applied.** **

And remember: always test your setup after, to see if everything is working as expected!

(Oh, by the way: this entry was written by Peter Molnar, and originally posted on petermolnar dot net.)