资源说明：Unofficial SVN Mirror for WordPress Plugin w3-total-cache

=== Plugin Name ===
Contributors: fredericktownes
Tags: user experience, cache, caching, page cache, css cache, js cache, db cache, disk cache, disk caching, database cache, http compression, gzip, deflate, minify, CDN, content delivery network, media library, performance, speed, multiple hosts, CSS, merge, combine, unobtrusive javascript, compress, optimize, optimizer, JavaScript, JS, cascading style sheet, plugin, yslow, YUI, google, google rank, google page speed, S3, CloudFront, AWS, Amazon Web Services, batcache, wp cache, wp super cache, w3 total cache, buddypress
Requires at least: 2.6
Tested up to: 2.9.1
Stable tag: 0.8.5.2

Improve the speed and user experience of your site. Add page caching, database caching, minify and content delivery network and more to WordPress.

== Description ==

The fastest and most complete WordPress performance optimization plugin. Trusted by many popular sites like: mashable.com, smashingmagazine.com, makeuseof.com, kiss925.com, lockergnome.com, tutsplus.com, johnchow.com, ilovetypography.com, webdesignerdepot.com, pearsonified.com, css-tricks.com, yoast.com and others — W3 Total Cache improves the user experience of your blog by improving your server performance, caching every aspect of your site, reducing the download time of your theme and providing transparent content delivery network (CDN) integration.

Benefits:

* At least 10x improvement in overall site performance (when fully configured: Grade A in [YSlow](http://developer.yahoo.com/yslow/) or significant [Google Page Speed](http://code.google.com/speed/page-speed/) improvements)
* Improves "[site performance](http://googlewebmastercentral.blogspot.com/2009/12/your-sites-performance-in-webmaster.html)" which [affect your site's rank](http://searchengineland.com/site-speed-googles-next-ranking-factor-29793) on Google.com
* "Instant" second page views (browser caching after first page view)
* Reduced page load time: increased visitor time on site (visitors view more pages)
* Optimized progressive render (pages appear to render immediately)
* Improved web server performance (sustain high traffic spikes)
* Up to 80% bandwidth savings via minify and HTTP compression of HTML, CSS, JavaScript and feeds

Features:

* Compatible with shared hosting, virtual private / dedicated servers and dedicated servers / clusters
* Transparent content delivery network (CDN) integration with Media Library, theme files and WordPress itself
* Caching of (minified and compressed) pages and posts in memory or on disk
* Caching of (minified and compressed) CSS and JavaScript in memory, on disk or on CDN
* Caching of feeds (site, categories, tags, comments) in memory or on disk
* Caching of search results pages (i.e. URIs with query string variables) in memory or on disk
* Caching of database objects in memory or disk
* Minification of posts and pages and feeds
* Minification (combine and remove comments / white space) of inline, embedded or 3rd party JavaScript (with automated updates)
* Minification (combine and remove comments / white space) of inline, embedded or 3rd party CSS (with automated updates)
* Browser caching of CSS, JavaScript and HTML using future expire headers and entity tags (ETag)
* JavaScript grouping by template (home page, post page etc) with embed location management
* Non-blocking JavaScript embedding
* Import post attachments directly into the Media Library (and CDN)

Improve the user experience for your readers without having to change WordPress, your theme, your plugins or how you produce your content.

== Frequently Asked Questions ==

= Why does speed matter? =

Speed is among the most significant success factors web sites face. In fact, your blog's speed directly affects your income (revenue) — it's a fact. Some high traffic sites conducted research and uncovered the following:

* Google.com: **+500 ms** (speed decrease) -> **-20% traffic loss** [[1](http://home.blarg.net/~glinden/StanfordDataMining.2006-11-29.ppt)]
* Yahoo.com: **+400 ms** (speed decrease) -> **-5-9% full-page traffic loss** (visitor left before the page finished loading) [[2](http://www.slideshare.net/stoyan/yslow-20-presentation)]
* Amazon.com: **+100 ms** (speed decrease) -> **-1% sales loss** [[1](http://home.blarg.net/~glinden/StanfordDataMining.2006-11-29.ppt)]

A thousandth of a second is not a long time, yet the impact is quite significant. Even if you're not a large company (or just hope to become one), a loss is still a loss. However, there is a solution to this problem, take advantage.

In the near future, search engines will weigh the performance of web sites as factors in their ranking algorithms. Search engine's have the goal of providing users with the best user experience, so speed is definitely a concern.

= Why is W3 Total Cache better than other cache plugins? =

**It's complete.** Most of the popular cache plugins available do a great job and serve their purpose very well. Our plugin remedies numerous performance reducing aspects of any web site going far beyond merely reducing CPU usage (load) and bandwidth consumption for HTML pages alone. Equally important, the plugin requires no theme modifications, modifications to your .htaccess (mod_rewrite rules) or programming compromises to reap the benefits. Most importantly, it's the only plugin designed to optimize all practical hosting environments. The options are many and setup is easy.

= I've never heard of any of this stuff; my blog is fine, no one complains about the speed. Why should I install this? =

Rarely do readers take the time to complain. They typically just stop browsing earlier than you'd prefer and may not return altogether. This is the only plugin specifically designed to make sure that all aspects of your site are as fast as possible. Google is placing more emphasis on the [speed of a site as a factor in rankings](http://searchengineland.com/site-speed-googles-next-ranking-factor-29793); this plugin helps with that too.

It's in every web site owner's best interest is to make sure that the performance of your blog is not hindering its success.

= And how many years of university do I need to use this thing? =

-4 - That's right; a youngster in junior high school can get started with this plugin. Seriously, if you did your own WordPress install or have ever installed a plugin before you're in good shape. If you need help, let us know or perhaps we'll make some videos or the like.

= Which WordPress versions are supported? =

To use all features in the suite, a minimum of version WordPress 2.6 with PHP 5 is required. Earlier versions will benefit from our Media Library Importer to get them back on the upgrade path and into a CDN of their choosing.

= What about comments? Does the plugin slow down the rate at which comments appear? =

On the contrary, as with any other action a user can perform on a site, faster performance will encourage more of it. The cache is so quickly rebuilt in memory that it's no trouble to show visitors the most current version of a post that's experiencing Digg, Slashdot, Drudge Report, Yahoo Buzz or Twitter effect.

= Will the plugin interfere with other plugins or widgets? =

No, on the contrary if you use the minify settings you will improve their performance by several times.

= Does this plugin work with WordPress MU? =

Indeed it does.

= Does this plugin work with BuddyPress (bbPress)? =

Yes.

= Will this plugin speed up WP Admin? =

Yes, indirectly - if you have a lot of bloggers working with you, you will find that it feels like you have a server dedicated only to WP Admin once this plugin is enabled; the result, increased productivity.

= Which web servers do you support? =

We are aware of no incompatibilities with [apache](http://httpd.apache.org/) 1.3+, [IIS](http://www.iis.net/) 5+ or [litespeed](http://litespeedtech.com/products/webserver/overview/) 4.0.2+. If there's a web server you feel we should be actively testing (e.g. [lighttpd](http://www.lighttpd.net/)), we're [interested in hearing](http://www.w3-edge.com/contact/).

= Is this plugin server cluster and load balancer friendly? =

Yes, built from the ground up with scale and current hosting paradigms in mind.

= What is the purpose of the "Media Library Import" tool and how do I use it? =

The media library import tool is for old or "messy" WordPress installations that have attachments (images etc in posts or pages) scattered about the web server or "hot linked" to 3rd party sites instead of properly using the media library.

The tool will scan your posts and pages for the cases above and copy them to your media library, update your posts to use the link addresses and produce a .htaccess file containing the list of of permanent redirects, so search engines can find the files in their new location.

You should backup your database before performing this operation.

= How do I find the JS and CSS to optimize (minify) them with this plugin? =

View your page source in your browser and search for any `