My performance probleme is solved.

After having done lots of tests that were suggested to me, I found 
that the the  bottle-neck was apache itself. In fact, the values of 
the MaxClients was to low to be efficient. I set it far higher (five 
times), and now, it works wonderfully !

Thank you to all who helped me, and I hope this can help those who 
told me they were having the same probleme.

-- 
J=E9r=F4me Duquennnoy
15, rue des Moli=E8res
91400 Gometz la Ville
tel : 01 60 12 37 32
       06 08 50 14 00