How to Optimize Web Site Performance

CodeProject

1. White Space Filtering through HTTP Module.
2. Merge all inline styles and multiple CSS into one big global css file.
3. Merge all inline javascripts and multiple javascript files into one big .js file and add reference to this file whenever you require.
4. Minify JavaScript and CSS files using CSS Optimizer and Free JavaScript Optimizer or any other tool which you like.
5. Try using less images in your web page.
6. Optimize your images with image optimizer I use Trout's GIF Optimizer to optimize gif files. PngOptimzer to optimize my PNG files, both the optimizer does not effect the quality of your image.
   
7. If your pagesize is increasing because of ViewState then try to save viewstate on server side. Here is a simpe example to Save ViewState on the File System

These six steps really helps your site in loosing the weight and they do not take much effort at all. After implementing these six steps see the performance of your application. If after that you are not satisfied enough then try following links:-
10 ASP.NET Performance and Scalability Secrets
Performance Optimization of ASP.NET Applications on Client-side

Also take a look at 15 Tools to Help You Develop Faster Web Pages.