apache 2.0 - number of httpd grows up + slow response

Hi,

i run the apache 2.0 on linux system. The number of httpd grows up
after I start the server a few hours later. Look at the following
Pids.

httpd(3383)

httpd(3499)

httpd(3690)

httpd(3720)

httpd(3743)

httpd(3757)

httpd(3826)

httpd(3982)

httpd(4682)

httpd(5386)

httpd(7643)

httpd(7668)

httpd(9452)

httpd(9508)

httpd(10171)

httpd(10915)

httpd(11092)

httpd(11422)

httpd(12543)

httpd(12718)

httpd(12722)

httpd(12735)

httpd(12760)

httpd(12766)

httpd(12785)

.....

There are about 200 httpd processes. I doubt the apache doesn't free
up the unused httpds processes whose PIDs are small ones for some kind
of reason. My MPM is prevoker. Finally the web server is slower and
slower.

My questions:
1. how can I free up the unused httpd processes?
2. why is the server so slow?

Here is the server's summary. The load average is very high, the cpu
and memory is not so high. And the server doesn't use Swap yet.
---------------------------------------------------------------------------------------------------------------------
19:46:16 up 4:45, 2 users, load average: 17.31, 32.41, 28.76
234 processes: 229 sleeping, 4 running, 1 zombie, 0 stopped
CPU states: cpu user nice system irq softirq iowait
idle
total 58.2% 0.0% 9.4% 0.0% 0.0% 0.0%
32.2%
Mem: 1000316k av, 508364k used, 491952k free, 0k shrd,
35828k buff
79460k active, 368260k inactive
Swap: 2097136k av, 0k used, 2097136k free
115060k cached
---------------------------------------------------------------------------------------------------------------------

Thanks a lot in advance!!!

Newbie