Uso de memória alta do PHP-FPM

Question

Eu tenho um blog wordpress, que usa o WP-SuperCache, e normalmente recebo 100 visitantes por dia. Com nginx + php-fpm é muito rápido, e não tenho arrependimentos.

Uma coisa que eu notei é que o php-fpm tem muita memória:

top - 09:20:43 up 5 days, 15:53,  1 user,  load average: 0.00, 0.00, 0.00
Tasks:  26 total,   1 running,  25 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.0%sy,  0.0%ni,100.0%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   1048576k total,   329956k used,   718620k free,        0k buffers
Swap:        0k total,        0k used,        0k free,        0k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
10226 www-data  15   0  145m  52m 4584 S  0.0  5.1   0:07.55 php-fpm
10223 www-data  16   0  141m  48m 4692 S  0.0  4.8   0:08.70 php-fpm
20277 www-data  15   0  138m  46m 4368 S  0.0  4.5   0:07.55 php-fpm
20259 www-data  15   0  133m  41m 4600 S  0.0  4.0   0:06.68 php-fpm
12201 www-data  15   0  133m  41m 4632 S  0.0  4.0   0:08.31 php-fpm
11586 www-data  15   0  132m  40m 4292 S  0.0  3.9   0:03.27 php-fpm
29822 www-data  15   0  128m  36m 4356 S  0.0  3.6   0:05.26 php-fpm
28427 mysql     15   0  200m 7300 4764 S  0.0  0.7   0:47.89 mysqld
10202 root      18   0 98.3m 4320 1204 S  0.0  0.4   0:03.80 php-fpm
22524 root      18   0 86064 3396 2652 S  0.0  0.3   0:16.74 sshd
 9882 www-data  18   0 42052 2572  804 S  0.0  0.2   0:27.52 nginx
 9884 www-data  18   0 42052 2560  804 S  0.0  0.2   0:26.26 nginx
 9881 www-data  18   0 42064 2524  804 S  0.0  0.2   0:29.24 nginx
 9879 www-data  18   0 42032 2480  804 S  0.0  0.2   0:29.58 nginx
23771 root      15   0 12176 1820 1316 S  0.0  0.2   0:00.08 bash
28344 root      22   0 11932 1416 1184 S  0.0  0.1   0:00.00 mysqld_safe
18167 root      16   0 62628 1208  648 S  0.0  0.1   0:00.55 sshd
25941 root      15   0 12612 1192  928 R  0.0  0.1   0:02.21 top
11573 root      15   0 20876 1168  592 S  0.0  0.1   0:00.67 crond
 9878 root      18   0 41000 1112  284 S  0.0  0.1   0:00.00 nginx
21736 root      23   0 21648  936  716 S  0.0  0.1   0:00.00 xinetd
11585 root      18   0 46748  816  428 S  0.0  0.1   0:00.00 saslauthd
14125 root      12  -4 12768  768  452 S  0.0  0.1   0:00.00 udevd
    1 root      18   0 10352  728  616 S  0.0  0.1   0:17.93 init
24564 root      15   0  5912  680  544 S  0.0  0.1   0:01.90 syslogd
11618 root      18   0 46748  548  160 S  0.0  0.1   0:00.00 saslauthd

Aqui está minha configuração do php-fpm:

[global]

pid = run/php-fpm.pid
error_log = log/php-fpm.log
log_level = notice

[www]

listen = 127.0.0.1:9000

user = www-data
group = www-data

pm = dynamic

pm.max_children = 50
pm.start_servers = 3
pm.min_spare_servers = 3
pm.max_spare_servers = 10
pm.max_requests = 500

Às vezes, chega a 400MB. E estou planejando adicionar um novo site no meu VPS. Isso é normal?