I've been making progress:
ab -k -n 25000 -c 500
http://pacura.ru/
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.
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oncurrency Level: 500
Time taken for tests: 40.164 seconds
Complete requests: 25000
Failed requests: 0
Write errors: 0
Keep-Alive requests: 0
Total transferred: 1065375000 bytes
HTML transferred: 1051000000 bytes
Requests per second: 622.44 [#/sec] (mean)
Time per request: 803.286 [ms] (mean)
Time per request: 1.607 [ms] (mean, across all concurrent requests)
Transfer rate: 25903.74 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 2.4 0 86
Processing: 6 795 725.5 590 3741
Waiting: 6 794 725.5 589 3740
Total: 6 795 726.0 590 3741
Percentage of the requests served within a certain time (ms)
50% 590
66% 874
75% 1137
80% 1293
90% 1700
95% 2396
98% 2918
99% 3232
100% 3741 (longest request)