Sharepoint is too slow (WSS)

Hi all !

I'm wondering why my sharepoint services are so slow. Each time I connect to my website I have to wait someting like 15-20 seconds (after the first connexion, it works fine). Each time I create a subsite, it's at least 20 seconds I have to wait...

Is this normal, or is there a way to speed up things ?

Thanks !

Z.

PS : It's not a hardware problem, hardware is far more sufficient in my case