Performance Tips & Tricks
Fiddler
Keep Requests Down to a Minimum
limit number of JavaScript & CSS calls by combining files
Make Use of Content Delivery Networks
edge cache - put JavaScript & CSS files closer to client
using Microsoft CDN 
    <script> src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.4.js" 
             type="text/javascript" </script>
full list of MS CDN supported JavaScript libraries and their associated URLs can be found at http://www.asp.net/ajaxLibrary/cdn.ashx
Google offers similar capabilities http://www.google.com/apis/libraries/devguide.html#AjaxLibraries
if using ScriptManager server control in ASP.NET 4 set EnableCdn attribute to true to use CDN 
    <asp:ScriptManager ID="ScriptManager1" EnableCdn="true" runat="server" />
Enable the Browser to Cache Items Longer
put scripts, stylesheets and images in dedicated folders
within these folders control how long they are cached on the client
using IIS
highlight folder with IIS manager
select HTTP Response Headers icon
double-clicking the icon will show list of headers that are currently sent from IIS for request
click Set Common Headers link to raise dialog
use dialog to expire content
dismissing the dialog by clicking OK creates a web.config file for the directory 
    <?xml version="1.0" encoding="UTF-8" ?>
    <configuration>
        <system.webServer>
            <staticContent>
                <clientCache cacheControlMode="UseMaxAge" cacheContentMaxAge="7.00:00:00" />
            </staticContent>
        </system.webServer>
    </configuration>
example sets cache time as 7 days
Enabling Content Compression
sample request header that supports compression 
    GET http://www.subdevo.com/ HTTP 1.1
    Accept: text/html, application/xhtml+xml, */*
    Accept-Language: en-US
    User-Agent: Mozilla/5.0 (compatible; mSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)
    Accept-Encoding: gzip, deflate
    Connection: Keep-Alive
    Host: www.subdevo.com
client can accept a compressed response
compressed responses consume less bandwidth
IIS 7
from IIS Manager highlight site
select Compression icon in list of available options
can enable static or dynamic compression
Location of Content in Pages
put all CSS references at top of page
put all JavaScript references at bottom of page
makes page appear to load faster
n4jvp.com