If you installed seo, you're getting hammered by spiders now since the search engines are all loving your site now and indexing every single page.

I unistalled seo, this is still hapening

Do you have access to your server logs? It seems like you should be able to tell if it's related to a high traffic load.

Also maybe you could use the Firefox browser and install an add-on called "Tamper Data", it lets you see every request that is made while loading a page, and how long they each took. Might tell you something, I don't know.

Its happens to the all members , also i do have access but this is not a problem with high traffic because it the usual traffic i have each day.

I noticed something strange that always for a few seconds the website work GOOD and it take him 3 seconds to get up and after 1 minute it return to slow and take him a 30 seconds to load up

You're not reading my suggestions, so I'll give it one last time and you can figure it out on your own....

What did your host say was slowing your site down, what kind of hosting do you have
What plugins and mods do you have installed

vbulletin alone isn't slow, it's something you or your host has done.

good luck
-Brandon

They don't know what is slowing my site , i have a simple host , NOT VPS , NOT Decided server, just host.

i have vbseo - sitemap generator , 5 latest posts , hide links, arcade , credits.

Disable your arcade and see if it makes a difference.

well the problem seems to be gone, i will wait 5 minutes to check it out and update you.

edit:

Well, :( Not worked

disable all plugins and see if that helps
if so, turn them on one by one until it lags up

i have to say , they didn't make any problems before, till i installed seo(rewrite) then i deleted it and its still making problems