Webservice in existing .net website

Question

Hi All...

My requirement is -

I have a ASP.NET Website with SQL Server 2008 as backend.

There is a Class Library with total 15 class files.

There are more than 3lacs records in each table (2 Masters and 1 Transaction Tables).

Because of this, the system is running very slow.

I want to know-
1. How do I add a WCF Service to this existing website so that the website runs smoothly.
2. Is there any other way in which I can handle this website.
3. The Dropdownlist also takes more time in loading.

Thanks a lot in advance.