Jeśli kogoś interesuje to zrobiłem mały test wydajności for PhpBB i JavaBB.
Sprzęt: X2 3600, 2GB ram, OpenSuse 11.0

JavaBB: Serwer Resin, Java 1.6.0_06-b02
Kod
Document Path:          /javabb/forum.jbb
Document Length:        9005 bytes

Concurrency Level:      40
Time taken for tests:   7.216379 seconds
Complete requests:      400
Failed requests:        225
   (Connect: 0, Length: 225, Exceptions: 0)
Write errors:           0
Total transferred:      3650133 bytes
HTML transferred:       3553733 bytes
Requests per second:    55.43 [#/sec] (mean)
Time per request:       721.638 [ms] (mean)
Time per request:       18.041 [ms] (mean, across all concurrent requests)
Transfer rate:          493.88 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   2.3      0      38
Processing:    29  690 857.7    384    4891
Waiting:        5  655 861.8    335    4889
Total:         29  690 857.7    384    4891

Percentage of the requests served within a certain time (ms)
  50%    384
  66%    561
  75%    890
  80%   1002
  90%   1716
  95%   2367
  98%   4155
  99%   4296
100%   4891 (longest request)


PhpBB: Serwer lighttpd, php 5.2.10 fastcgi, xcache
Kod
Document Path:          /phpbb/index.php
Document Length:        10151 bytes

Concurrency Level:      40
Time taken for tests:   9.116953 seconds
Complete requests:      400
Failed requests:        0
Write errors:           0
Total transferred:      4286069 bytes
HTML transferred:       4060400 bytes
Requests per second:    43.87 [#/sec] (mean)
Time per request:       911.695 [ms] (mean)
Time per request:       22.792 [ms] (mean, across all concurrent requests)
Transfer rate:          459.03 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.6      0       3
Processing:   132  871 155.8    855    1458
Waiting:      113  861 155.7    846    1440
Total:        135  871 155.6    855    1459

Percentage of the requests served within a certain time (ms)
  50%    855
  66%    871
  75%    884
  80%    901
  90%    980
  95%   1195
  98%   1324
  99%   1381
100%   1459 (longest request)