Speeding Up Your Website

fellows I will give you five hints which must be took in consideration for speeding up a website/application
each hint is a topic by it self.

1.Decrease the size of view state.
2.Decrease the bandwidth that the site is using.
3.Enabling HTTP Compression Support in IIS 6
4.Use Caching
5.In ASPX form place the jqueries at the bottom and the CSS code at the top

with respect to database also these issues slows down your website:

Lack of Indexes : The ability to index data is one of the key benefits of storing information in a database.

Poorly Written Queries

Deadlocks:Databases use locks to prevent your data from being messed up by conflicting updates.

Hardware Issues: As with any software application, SQL Server performs at its optimum when it's running on sufficiently powerful hardware.