How to force Apache to kill a process upon termination?

Question

Apache HTTP Server

Hello. :)
I have a website where you can upload your videos. My server in this case works as a transshipment point and after a person has uploaded a video to it, he starts transferring it to the video hosting. And it is at this moment of transmission that he begins to fill up RAM and SWAP for such a number of places as this video occupied. Actually, this is not a problem, let it take it, BUT, after the end of the script, the memory is not released instantly! She begins to free herself sooo slowly, and this is very disturbing, because. there may be another rather weighty video on the way.
VPS parameters: 1024mb RAM, 2048mb SWAP.
My httpd settings:

Timeout 60
KeepAlive On
MaxKeepAliveRequests 100
KeepAliveTimeout 5

<IfModule prefork.c>
StartServers       1
MinSpareServers    1
MaxSpareServers    10
ServerLimit       20
MaxClients        20
MaxRequestsPerChild  150
</IfModule>

It would be ideal if the httpd process would exit immediately after the end, and not hang for as long as it likes. Does anyone know how to implement this?