when using Captive Portal, CPU usage increases to %80

when using Captive Portal, CPU usage increases to 80%..and my top processes are as below..
but i don't know which php file that Captive Portal uses, causes this high cpu usage...

PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
30143 root 1 110 0 110M 26284K RUN 0 0:25 66.36% php
21541 root 1 110 0 110M 26292K CPU1 1 0:26 63.48% php
51474 root 1 76 0 113M 26700K piperd 0 0:22 58.25% php
53347 root 1 108 0 113M 26636K CPU0 0 0:10 57.08% php
18854 root 1 107 0 113M 26640K RUN 2 0:11 49.66% php
17848 root 1 105 0 112M 26460K RUN 1 0:07 43.55% php
18139 root 1 104 0 110M 26184K CPU5 5 0:06 38.57% php
8127 root 1 76 0 112M 33992K piperd 5 1:29 9.57% php
60130 root 1 97 0 110M 26156K CPU4 4 0:01 7.67% php
34213 root 1 47 0 34120K 11916K kqread 7 2:12 4.39% lighttpd
51285 root 1 45 0 14848K 2944K select 1 4:27 1.56% syslogd
24353 root 1 44 0 44456K 37236K bpf 6 36:16 0.00% tcpdump
24582 root 1 44 0 5880K 1068K piperd 6 23:21 0.00% logger
16728 root 1 76 20 7004K 1420K kqread 3 5:51 0.00% check_reload_status
5215 dhcpd 1 44 0 145M 132M select 4 5:14 0.00% dhcpd
30230 root 1 64 20 5880K 1524K select 0 4:55 0.00% apinger
37627 root 1 44 0 13984K 6852K select 4 4:09 0.00% ntpd
49520 root 1 44 0 31052K 10464K kqread 2 1:10 0.00% lighttpd

another snapshot of top command...

$ top
last pid: 6624; load averages: 7.20, 6.72, 6.51 up 16+15:23:18 11:20:02
92 processes: 3 running, 89 sleeping

Mem: 287M Active, 61M Inact, 364M Wired, 164K Cache, 407M Buf, 15G Free
Swap: 32G Total, 32G Free

PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
37733 root 1 76 0 113M 26864K sysctl 5 0:24 70.90% php
54077 root 1 76 0 113M 26732K sysctl 1 0:17 66.55% php
53135 root 1 76 0 113M 26696K sysctl 4 0:17 65.87% php
53461 root 1 110 0 110M 26348K CPU0 0 0:16 63.38% php
49866 root 1 76 0 113M 26760K piperd 1 0:18 60.16% php
51152 root 1 76 0 113M 26692K piperd 4 0:17 51.07% php
4659 root 1 99 0 112M 26476K CPU7 7 0:02 17.48% php
1955 root 1 71 0 112M 35352K piperd 3 0:18 6.79% php
10723 root 1 46 0 30024K 8128K kqread 0 0:22 4.49% lighttpd
51285 root 1 45 0 14848K 2944K select 3 5:50 1.66% syslogd
24353 root 1 44 0 44456K 37284K bpf 3 36:31 0.00% tcpdump
24582 root 1 44 0 5880K 1068K piperd 1 23:30 0.00% logger
16728 root 1 76 20 7004K 1420K kqread 6 8:09 0.00% check_reload_status
5215 dhcpd 1 44 0 145M 132M select 0 5:18 0.00% dhcpd
30230 root 1 64 20 5880K 1524K select 4 4:58 0.00% apinger
37627 root 1 44 0 13984K 6852K select 3 4:11 0.00% ntpd
54402 root 1 46 0 112M 34480K accept 7 3:08 0.00% php
49520 root 1 44 0 31052K 10464K kqread 3 1:11 0.00% lighttpd