Some delay for spawning process a second time

Hi -

Setup based on Apache (2.2.3-4+etch5) + libapache2-mod-fastcgi (2.4.2-8) 
+  php5-cgi (5.2.6-0.dotdeb.1)

Everything is working fine with this setup except for an abnormal long 
delay for spawning a new php5-cgi through suexec for the second time 
(after the first one has been killed).

Way to repeat the problem:

1. Apache just (re)started
2. Access to a virtualhost, say http://test.mydomain.com
	This takes approx. 0.5s which is fine
2. Access to this site again
	This takes approx. 0.04s which is still fine
3. Wait that the spawned process php5-cgi for this virtualhost is killed 
by fcgi-pm. Then access to the site again. Now it takes more than 3s to 
get the php5-cgi spawned. After that, time access is back to normal 
(~0.04s) untill the process is killed (then the 3s delay come back for 
the next spawn).

I have this in my Apache conf:

FastCgiWrapper /usr/local/lib/apache2/suexec-fcgi
FastCgiConfig -minProcesses 0 -maxClassProcesses 1 -maxProcesses 300 \
	-processSlack 30 -singleThreshold 20 -killInterval 240
AddHandler php5-fastcgi .php .php3 .php4 .php5
<Location /cgi-bin/php5-fcgi>
	SetHandler fastcgi-script
	Options +ExecCGI
</Location>
Action php5-fastcgi /cgi-bin/php5-fcgi
AddType application/x-httpd-php .php5

And this is the cgi-bin/php5-fcgi wrapper:
#!/bin/sh
export PHPRC="/web/s/t/test/php-configs/php5/"
export PHP_FCGI_CHILDREN=0
export PHP_FCGI_MAX_REQUESTS=1000
exec /usr/bin/php5-cgi

I spends some time attaching strace to fcgi-pm and Apache process, but I 
sadly didn't get a chance to figure out what could be the problem.

Does this sound to someone?

Any help/hint/idea will be greatly appreciated. Thanks in anticipation!

Regards,
-- 
Olivier Le Cam
CRDP de l'académie de Versailles