Drupal Caching

Drupal 5.0 With caching off

ab -c100 -n10 http://example.com/index.php
This is ApacheBench, Version 2.0.41-dev <$Revision: 1.141 > apache-2.0
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright (c) 1998-2002 The Apache Software Foundation, http://www.apache.org/

Benchmarking example.com (be patient).....done

Server Software:        Apache/2.0.59
Server Hostname:        example.com
Server Port:            80

Document Path:          /index.php
Document Length:        10541 bytes

Concurrency Level:      100
Time taken for tests:   3.417284 seconds
Complete requests:      10
Failed requests:        6
  (Connect: 0, Length: 6, Exceptions: 0)
Write errors:           0
Total transferred:      110154 bytes
HTML transferred:       104774 bytes
Requests per second:    2.93 [#/sec] (mean)
Time per request:       34172.840 [ms] (mean)
Time per request:       341.728 [ms] (mean, across all concurrent requests)
Transfer rate:          31.31 [Kbytes/sec] received

Connection Times (ms)
             min  mean[+/-sd] median   max
Connect:       92   93   0.6     93      94
Processing:  1351 2433 652.3   2757    3322
Waiting:     1158 2222 668.5   2566    3129
Total:       1444 2526 652.6   2850    3416

Percentage of the requests served within a certain time (ms)
 50%   2850
 66%   3059
 75%   3087
 80%   3095
 90%   3416
 95%   3416
 98%   3416
 99%   3416
100%   3416 (longest request)

Drupal 5.0 With caching on (Normal)

[sam@vps ~]$ ab -c100 -n10 http://example.com/index.php
This is ApacheBench, Version 2.0.41-dev <$Revision: 1.141 > apache-2.0
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright (c) 1998-2002 The Apache Software Foundation, http://www.apache.org/

Benchmarking example.com (be patient).....done

Server Software:        Apache/2.0.59
Server Hostname:        example.com
Server Port:            80

Document Path:          /index.php
Document Length:        10435 bytes

Concurrency Level:      100
Time taken for tests:   0.506276 seconds
Complete requests:      10
Failed requests:        0
Write errors:           0
Total transferred:      148446 bytes
HTML transferred:       139122 bytes
Requests per second:    19.75 [#/sec] (mean)
Time per request:       5062.760 [ms] (mean)
Time per request:       50.628 [ms] (mean, across all concurrent requests)
Transfer rate:          284.43 [Kbytes/sec] received

Connection Times (ms)
             min  mean[+/-sd] median   max
Connect:       93   93   0.7     93      94
Processing:   264  326  53.6    323     412
Waiting:      127  196  41.4    203     282
Total:        358  420  53.5    417     505

Percentage of the requests served within a certain time (ms)
 50%    417
 66%    430
 75%    473
 80%    492
 90%    505
 95%    505
 98%    505
 99%    505
100%    505 (longest request)

Drupal 5.0 With caching on (aggressive)

[sam@vps ~]$ ab -c100 -n10 http://example.com/index.php
This is ApacheBench, Version 2.0.41-dev <$Revision: 1.141 INSERT:CONTENT:ENDgt; apache-2.0
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright (c) 1998-2002 The Apache Software Foundation, http://www.apache.org/Benchmarking example.com (be patient).....done

Server Software:        Apache/2.0.59
Server Hostname:        example.com
Server Port:            80

Document Path:          /index.php
Document Length:        10541 bytes

Concurrency Level:      100
Time taken for tests:   0.469280 seconds
Complete requests:      10
Failed requests:        0
Write errors:           0
Total transferred:      144128 bytes
HTML transferred:       134804 bytes
Requests per second:    21.31 [#/sec] (mean)
Time per request:       4692.800 [ms] (mean)
Time per request:       46.928 [ms] (mean, across all concurrent requests)
Transfer rate:          298.33 [Kbytes/sec] received

Connection Times (ms)
             min  mean[+/-sd] median   max
Connect:       92   92   0.9     93      93
Processing:   245  314  44.4    336     377
Waiting:      133  162  19.0    169     188
Total:        338  407  44.3    429     469
WARNING: The median and mean for the initial connection time are not within a normal deviation
       These results are probably not that reliable.

Percentage of the requests served within a certain time (ms)
 50%    429
 66%    430
 75%    440
 80%    464
 90%    469
 95%    469
 98%    469
 99%    469
100%    469 (longest request)

Ponder Results

wow, certainly not a thorough test by any strech, but from ~3 req/sec (caching off) to ~20 req/sec with it on!
That is a quite impressive gain, 85%.