http://gtmetrix.com  

http://mscd.codeplex.com/  

fif:

Private Function addCache(days As Double) As String
With Current.Response
Response.Cache.SetCacheability(HttpCacheability.Public)
Response.Cache.SetMaxAge(TimeSpan.FromDays(days))
Response.Cache.SetExpires(DateTime.UtcNow.AddDays(days))
End With
End Function

The following XML shows and example of setting clientCache to specify a maximum age of 3 days:

<configuration>  
 <system.webServer>        
  <staticContent>            
   <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="3.00:00:00" />        
  </staticContent>  
 </system.webServer>
</configuration>