XF 1.1 XF Excessive processes running under user

[swatme]

hi

i have a vps with 4GB of ram
and i install 4 instllations of xf with different domains each

but still im getting this error often in these xf sites :
Excessive processes running under user xxxx

User:xxxx PID:30963 PPID:30227 Run Time:39(secs) Memory:162452(kb) exe:/usr/bin/php cmd:/usr/bin/php /home/xxxx/public_html/index.php
User:xxxx PID:30971 PPID:28856 Run Time:36(secs) Memory:162340(kb) exe:/usr/bin/php cmd:/usr/bin/php /home/xxxx/public_html/index.php
User:xxxx PID:30972 PPID:30752 Run Time:36(secs) Memory:162388(kb) exe:/usr/bin/php cmd:/usr/bin/php /home/xxxx/public_html/index.php
User:xxxx PID:31062 PPID:30826 Run Time:17(secs) Memory:161564(kb) exe:/usr/bin/php cmd:/usr/bin/php /home/xxxx/public_html/index.php
User:xxxx PID:31063 PPID:30662 Run Time:17(secs) Memory:162708(kb) exe:/usr/bin/php cmd:/usr/bin/php /home/xxxx/public_html/index.php
User:xxxx PID:31106 PPID:30643 Run Time:12(secs) Memory:13492(kb) exe:/usr/bin/php cmd:/usr/bin/php /home/xxxx/public_html/index.php
User:xxxx PID:31122 PPID:30887 Run Time:10(secs) Memory:13492(kb) exe:/usr/bin/php cmd:/usr/bin/php /home/xxxx/public_html/index.php

What shall i do? please help thanks