vBulletin taking down the servers

[daimpa]

Hello,

I'm having some troubles with vBulletin, converted in UTF 8, with only image category plugin. With an average of 50 users online at the same moment, it has been able to put offline 2 CPU, 16GB RAM and 4 disk raid-10. I had problems also at 5AM of morning, with almost 2 users online. I've vBulletin 4.2.0, and I'm on a cloud hosting. The hosting told me that the problem is that there're too many php process, caused maybe by normal users, spiders and robots.

They continue to tell me "we've noticed too many php process, please check them out", and they send me these lines:
user-2104 22814 0.0 0.4 465640 63720 ?? I 3:17PM 0:09.47 /usr/local/bin/php-cgi -d apc.enabled=0
user-2104 24616 0.0 0.3 449124 48484 ?? S 3:18PM 0:06.11 /usr/local/bin/php-cgi -d apc.enabled=0
user-2104 24640 0.0 0.3 453220 52504 ?? S 3:19PM 0:03.84 /usr/local/bin/php-cgi -d apc.enabled=0
user-2104 25678 0.0 0.4 469864 61948 ?? S 3:19PM 0:03.49 /usr/local/bin/php-cgi -d apc.enabled=0

But I've NO IDEA about what do these lines means! They said that problably there's something wrong with vBulletin.

This is the website: http://pesfan.it/

Really, I've no idea about what I should/could do. Any help please?