Joomla is a fairly populate content management system (CMS). It is a common sense that most Web sites have content that does not change frequently should use caching techniques to reduce load to server and improve end user experience. Joomla itself has three levels of caching:

1. Page caching
2. View caching
3. Module caching

Page caching is the one that significantly improves performance (8 times faster). However, the cache result (in html format) is saved as a php file in docroot/cache/page directory. IOW, php is still invoked to serve these pages.

LiteSpeed webserver (LSWS) cache bypasses php invocation and serves cached page directly from LSCache. Hence a much bigger performance improvement can be achieved.

To work with Joomla (cached for either guest visitor or logged-in user), LSCache relies on a cookie token to differentiate whether a user is logged in or not. However, Joomla assigns cookie to any user (guest and logged-in). cookie value changes as same session go through different stage (such as before login, after login, logout and log back in, etc) while cookie key stays the same. The easy way is the create desired cookie in joomla by modifying its code (small modification in login/logout stage). Login/Logout functions are located in the standard user component (docroot/component/com_user/controller.php).

The modification is as follows:

function login() {
                if(!JError::isError($error))
                {
                        // Redirect if the return url is not registration or login
                        if ( ! $return ) {
                                $return = 'index.php?option=com_user';
                        }
                        setcookie("loginuser","yes");     //  <==== add this line  # add "loginuser=yes" cookie upon successful login
                       $mainframe->redirect( $return );

function logout ()
                if(!JError::isError($error))
                {
                        setcookie("loginuser", "", time()-86400*365);  // <=== add this line # drop "loginuser" cookie upon logout.
                        if ($return = JRequest::getVar('return', '', 'method', 'base64')) {
                                $return = base64_decode($return);
                                if (!JURI::isInternal($return)) {
                                        $return = '';
                                }
                        }

Once test ok, implement rewrite rules to enable LSCache for the resources that required caching.

In file joomla_docroot/.htaccess

########## Begin - Joomla! core SEF Section
#
RewriteRule p.php - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !^/index.php
RewriteCond %{REQUEST_URI} (/|\.php|\.html|\.htm|\.feed|\.pdf|\.raw|/[^.]*)$  [NC]
RewriteRule (.*) index.php 
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
#
########## End - Joomla! core SEF Section

Change to

########## Begin - Joomla! core SEF Section
#
RewriteRule p.php - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !^/index.php
RewriteCond %{REQUEST_URI} (/|\.php|\.html|\.htm|\.feed|\.pdf|\.raw|/[^.]*)$  [NC]
RewriteRule (.*) index.php 
#### There is no need for this ENV
#RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
#
########## End - Joomla! core SEF Section

########## Begin - Rules for LSCache
RewriteCond %{REQUEST_METHOD} ^HEAD|GET$
RewriteCond %{HTTP_COOKIE} !loginuser
RewriteCond %{ORG_REQ_URI} !^/index.php$
RewriteCond %{ORG_REQ_URI} !^/administrator/
RewriteCond %{ORG_REQ_URI} (\.php|\.html|\.htm|\.feed|\.pdf|\.raw|/[^.]*)$  [NC]
RewriteRule .* - [E=Cache-Control:max-age=300,L]
########## End - Rules for LSCache

Explanation of the added rules:

1. Only cache for Head or Get requests
2. Cache for guest user (no loginuser cookie)
3. Cache request to any URLs like ((\.php|\.html|\.htm|\.feed|\.pdf|\.raw|/[^.]*)$) but excluding /index.php, and /administrator/*
4. Cache for 300 seconds

Note:

1. Joomla's login form (index.php) is not cache friendly (contain a security token) and has to be excluded from being cached.
2. /administrator/* is the Joomla backend. No need to be cached.

LSCache Policy configuration (Admin Console → Server/Vhost →Cache→ Cache Policy).

Cache Policy:

Enable Cache:	==> No
Cache Expire Time (seconds):	=>  Not Set
Cache Request with Query String:	=>  Yes
Cache Request with Cookie:	=>  Yes
Cache Response with Cookie:	=>  Yes
Ignore Request Cache-Control:	=>  Yes
Ignore Response Cache-Control:	=>  Yes
Enable Private Cache:  => Yes
Private Cache Expire Time (seconds):  => 120

To verify if a resource is served out of LSCache is simple, just look for “X-LiteSpeed-Cache: hit,private” in server response header. If the header is present, the resource IS served from LSCache.

HTTP/1.1 200 OK
Content-Encoding: gzip
Vary: Accept-Encoding
Date: Tue, 08 Feb 2011 23:14:38 GMT
Server: LiteSpeed
Connection: Keep-Alive
Keep-Alive: timeout=5, max=100
**[COLOR="red"]X-LiteSpeed-Cache: hit,private[/COLOR]**
Content-Length: 6141
X-Powered-By: PHP/5.2.11
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"
Content-Type: text/html; charset=utf-8
Expires: Mon, 1 Jan 2001 00:00:00 GMT
Last-Modified: Tue, 08 Feb 2011 23:14:12 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache

Following is the ab benchmark of the test sites in our lab against latest Joomla 1.5 (1.5.22) with sample data comes with install.

Litespeed Cache + Joomla 1.5.22 (with NO system cache plugin)

 
Benchmarking 192.168.0.56 (be patient).....done


Server Software:        LiteSpeed/4.1RC4
Server Hostname:        192.168.0.56
Server Port:            8088

Document Path:          /joomla-overview.html
Document Length:        12422 bytes

Concurrency Level:      10
Time taken for tests:   0.139489 seconds
Complete requests:      100
Failed requests:        0
Write errors:           0
Total transferred:      1363478 bytes
HTML transferred:       1316732 bytes
Requests per second:    716.90 [#/sec] (mean)
Time per request:       13.949 [ms] (mean)
Time per request:       1.395 [ms] (mean, across all concurrent requests)
Transfer rate:          9541.97 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:     5   12   4.2     12      22
Waiting:        5   11   3.9     11      21
Total:          5   12   4.2     12      22

Percentage of the requests served within a certain time (ms)
  50%     12
  66%     12
  75%     13
  80%     15
  90%     21
  95%     21
  98%     22
  99%     22
 100%     22 (longest request)

Joomla 1.5.22 with Page Caching (system cache plugin)

 
Benchmarking 192.168.0.56 (be patient).....done


Server Software:        LiteSpeed/4.1RC4
Server Hostname:        192.168.0.56
Server Port:            8088

Document Path:          /joomla-overview.html
Document Length:        12537 bytes

Concurrency Level:      10
Time taken for tests:   2.492758 seconds
Complete requests:      100
Failed requests:        0
Write errors:           0
Total transferred:      1306000 bytes
HTML transferred:       1253700 bytes
Requests per second:    40.12 [#/sec] (mean)
Time per request:       249.276 [ms] (mean)
Time per request:       24.928 [ms] (mean, across all concurrent requests)
Transfer rate:          511.48 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:    51  243 159.6    215    1226
Waiting:       43  203 147.5    181    1080
Total:         51  243 159.6    215    1226

Percentage of the requests served within a certain time (ms)
  50%    215
  66%    256
  75%    275
  80%    283
  90%    324
  95%    436
  98%    959
  99%   1226
 100%   1226 (longest request)

Joomla 1.5.22 with NO Page Caching

Benchmarking 192.168.0.56 (be patient).....done


Server Software:        LiteSpeed/4.1RC4
Server Hostname:        192.168.0.56
Server Port:            8088

Document Path:          /joomla-overview.html
Document Length:        12490 bytes

Concurrency Level:      10
Time taken for tests:   9.218677 seconds
Complete requests:      100
Failed requests:        92
   (Connect: 0, Length: 92, Exceptions: 0)
Write errors:           0
Total transferred:      1296527 bytes
HTML transferred:       1246727 bytes
Requests per second:    10.85 [#/sec] (mean)
Time per request:       921.868 [ms] (mean)
Time per request:       92.187 [ms] (mean, across all concurrent requests)
Transfer rate:          137.33 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.9      0       5
Processing:   256  893 578.1    748    3065
Waiting:      248  828 567.9    694    2878
Total:        256  893 578.1    748    3065

Percentage of the requests served within a certain time (ms)
  50%    748
  66%    868
  75%    933
  80%   1058
  90%   1672
  95%   2396
  98%   2892
  99%   3065
 100%   3065 (longest request)