ab for nginx+php-fpm and nginx+hhvm ... we have a winner.

nginx+hhvm

root@ubuntu:/# ab -c 1000 -n 10000 http://localhost/misc/wp_dev/index.php
This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient)
Completed 1000 requests
Completed 2000 requests
Completed 3000 requests
Completed 4000 requests
Completed 5000 requests
Completed 6000 requests
Completed 7000 requests
Completed 8000 requests
Completed 9000 requests
Completed 10000 requests
Finished 10000 requests


Server Software:        nginx/1.4.7
Server Hostname:        localhost
Server Port:            80

Document Path:          /misc/wp_dev/index.php
Document Length:        172 bytes

Concurrency Level:      1000
Time taken for tests:   0.581 seconds
Complete requests:      10000
Failed requests:        0
Write errors:           0
Non-2xx responses:      10000
Total transferred:      3230000 bytes
HTML transferred:       1720000 bytes
Requests per second:    17202.38 [#/sec] (mean)
Time per request:       58.132 [ms] (mean)
Time per request:       0.058 [ms] (mean, across all concurrent requests)
Transfer rate:          5426.14 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    4  10.1      0      43
Processing:     0   10  12.6      6     221
Waiting:        0   10  12.6      6     221
Total:          1   14  20.1      7     223

Percentage of the requests served within a certain time (ms)
  50%      7
  66%      8
  75%      9
  80%     10
  90%     51
  95%     67
  98%     82
  99%     87
 100%    223 (longest request)
root@ubuntu:/#

nginx+php-fpm

root@ubuntu:/# ab -c 1000 -n 10000 http://localhost/misc/wp_dev/index.php
This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient)
Completed 1000 requests
Completed 2000 requests
Completed 3000 requests
Completed 4000 requests
Completed 5000 requests
Completed 6000 requests
Completed 7000 requests
Completed 8000 requests
Completed 9000 requests
Completed 10000 requests
Finished 10000 requests


Server Software:        nginx/1.4.7
Server Hostname:        localhost
Server Port:            80

Document Path:          /misc/wp_dev/index.php
Document Length:        192 bytes

Concurrency Level:      1000
Time taken for tests:   2.388 seconds
Complete requests:      10000
Failed requests:        9361
Write errors:           0
Non-2xx responses:      10000
Total transferred:      3239762 bytes
HTML transferred:       1694252 bytes
Requests per second:    4187.83 [#/sec] (mean)
Time per request:       238.787 [ms] (mean)
Time per request:       0.239 [ms] (mean, across all concurrent requests)
Transfer rate:          1324.96 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0   37 178.2      0    1002
Processing:     0   41 169.3     14    1569
Waiting:        0   41 169.3     14    1569
Total:          0   78 263.7     15    2323

Percentage of the requests served within a certain time (ms)
  50%     15
  66%     22
  75%     28
  80%     35
  90%     58
  95%    474
  98%   1206
  99%   1296
 100%   2323 (longest request)
root@ubuntu:/#