We have started to document several techniques to improve responsiveness on webforms (Webforms - Top 10 Tasks to Improve Responsiveness.docx). Here are the high level bullets:

1. Only use ViewState when necessary
2. Set the ScriptManager LoadScriptsbeforeUI property to false
3. Combine Client Scripts into a Composite Script
4. Minimize the content of the UpdatePanel to reduce ViewState
5. Use UpdatePanels when using Custom Validators
6. Don't use LinkButton controls, use Button controls instead

If you have additional tips/tasks. Please add to this discussion.

Thanks,

-Francis

#1 way to improve responsiveness: Use extensive data caching within your ASP.NET app to reduce round-trips to the database.

#2 way to improve responsiveness: Combine data requests to reduce round-trips to the database.

#3 way to improve responsiveness: Study your sql queries and do whatever it takes to optimize them, especially those that are frequently executed. Focus on reducing query complexity (i.e. O[N] rather than O[N^2], etc) whenever possible.

#4 way to improve responsiveness: Do not use Repeater or any other data-binding control. For some reason, data-binding is much much slower than a simple for or foreach loop.

#5 way to improve responsiveness: Turn on tracing, add tracing statements to your code, identify your bottlenecks, and focus on those areas specifically.