How to speed up Wordpress

Since the time it takes to a site displaying pages became a positioning factor for Google (not the most important but not negligible), one may wonder how to speed up a Wordpress site, while the speed depends mainly of the CMS.
But it is nevertheless possible to make it faster by optimizing it.

Set cached pages

This is the easiest way, and also the most misunderstood. Caching avoids repetitive access to the database to retrieve the same data, again and again. For this there are plugins to install.

List of cache manager plugins updated recently:

The following definition in wp-config.php is recommended by some blogs or even very popular sites:

define ('ENABLE_CACHE', true)  // OBSOLETE

In reality it is not implemented since version 2.5 (three years ago!) It has no effect. This other alternative definition is supposed to have, but only in combination with one of persistent cache plugins mentioned above:

 define ('WP_CACHE', true)

Disable revisions

While you edit the wp-config.php file, take the time to disable revisions, to prevent the database from growing unnecessarily, this also slows down data access.

define ('WP_POST_REVISIONS', false);

Purge the theme

Choose a theme entirely preset can have drawbacks, because it contains any information, graphic or hidden, useful to some types of sites, but that is of no use for yours.

It is therefore necessary to see the source code and remove - with care - the useless fields and meta, this shrink the pages and contributes to an instant display.
If this seems too complicated, it is best to try other less overburdened themes.

Much information is given generically by the theme. Example for the site name:

<?php echo bloginfo (name); ?>

This is normal since the theme is designed for different sites and it does not know their name. But you know the name of your site and you can place a clear name:

Mysite.com

Similarly for the set of characters, it never changes on a site:

<meta http-equiv="content-type" content="<?php bloginfo('html_type') ?>; charset=<?php bloginfo('charset') ?>" />
<meta http-equiv="content-type" content="text/html; charset=UTF-8">

Only should be kept PHP calls that depend on the post, as its title for example.

Purge plugins

Remove all unused or non-essential plugins. More specifically, the statistics plugins, they tend to saturate the database and slow down the display.

Choose images

Use the most appropriate format for images. GIF and PNG are suitable for drawings, JPG for photos. Try to recompress images because even with the appropriate file format, tools are not equal in performance.
And about the JPG images, increasing the compression ratio makes sometimes little difference for the image quality and a lot for the size.

Besides that, it is best when the image is not the main topic of the article, to replace it with a thumbnailr on which user must click to see a full size image. This is something that Wordpress handles very well.

Reduce dependencies

While some services like Analytics are essential, many others are not necessarily. Depending on other sites is the best way to slow his own, and sometimes even block it when the other site does not respond.

But if you want to put JavaScript code for linking services, social sites, for example, place this code at the bottom of the page to let it displayed before they block it eventually.

Optimize Wordpress

The admin panel has several options that can speed up the display. Among them:

Conclusion

The last thing we can do to optimize a site: reducing the length of the text by summarizing or dividing in sections.
By dividing the article, I mean split the topic into two topics can each deserves an own article.
Divide the page into several pages, as it often made, to display more ads is something different. We tend to forget that the popularity of a site depends mainly on the satisfaction of readers.

See also