slow server, how to solve? & some frontpage questions

[Autosoft]

I'm a new user to plesk, never worked with it before.

My boss purchased a Plesk 7.5.4 server for windows.

Because we are an internet/webdesign company, we are hosting all our websites on this one server.
And because we're the administrators for a lot of websites, we've created al the domains/websites under 1 client.

This means: we have 1 client who "owns" 680 different domains.
and now our server is running terribly slow.

Could it be that the server is running this slow because we've created all domains under one client, and will this problem be solved if we create more clients and spread the domains over all the clients?

Please give me feedback on this one, it's a very important issue right now.


Thank you very much for your help,
í really don't know how to solve this.


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I've also got one question about using frontpage extentions;
When i create a so called "web user", i am able to log in on ftp with this user name and password, but when i try to login with frontpage, the user/password is not recognised.
And i did activate frontpage authoring.

ho to solve?