I have noticed the same problem as the user in bug #12507.

[root@www libexec]# mtrace ./libphp4.so.bak

Memory not freed:
-----------------
           Address     Size     Caller
000000000000000000        0  at

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This version has the php-4.0.6-memlimit.diff patch applied. A few httpd processes will consume large amounts of memory and processor, Apache must be stopped and restarted to free it. We did not notice these issues untill v4.0.5/4.0.6

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System Linux www.xxxxxxxx.com 2.2.19pre7 #1 SMP Wed Jan 24 17:04:44 CST 2001 alpha unknown 
Build Date Aug 13 2001 
Configure Command  './configure' '--with-apxs=/usr/local/apache/bin/apxs' '--with-config-file-path=/usr/local/apache' '--with-gd' '--with-zlib' '--with-gettext' '--enable-versioning' '--enable-inline-optimization' '--disable-debug' '--enable-memory-limit' '--disable-display-source' '--enable-sysvshm' '--enable-sysvsem' '--with-mysql=/usr' '--with-bz2' '--with-freetype' '--enable-shared' 
Server API Apache 
Virtual Directory Support disabled 
Configuration File (php.ini) Path /usr/local/apache/php.ini 
ZEND_DEBUG disabled 
Thread Safety disabled 

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memory_limit 24M 24M

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APACHE_INCLUDE   
APACHE_TARGET   
Apache Version Apache/1.3.20 
Apache Release 10320100 
Apache API Version 19990320 
Hostname:Port www.goquest.com:80 
User/Group nobody(99)/99 
Max Requests Per Child: 10000<br>Keep Alive: on<br>Max Per Connection: 75 
Timeouts Connection: 300<br>Keep-Alive: 15 
Server Root /usr/local/apache 
Loaded Modules mod_gzip, mod_php4, mod_setenvif, mod_access, mod_so, mod_auth, mod_alias, mod_userdir, mod_asis, mod_cgi, mod_dir, mod_autoindex, mod_include, mod_status, mod_negotiation, mod_mime, mod_log_config, mod_env, mod_php3, http_core 

 
Peter