Thank you guys for reply.
the problem of speed, is not because of my host, it is a good host and many large website hosted on it:
http://www.linode.com/
i think i need to optamize my vps cause it is unmanaged.
@champ of champs : iam using VPS in linode as i mentioned (the second plan) , not a shared host.
i'll try to solve this problem and look forward for my rerating.

Regards.