Hi Scot,

The primary mechanism for preventing duplicate transactions is disabling the submit button which we have already implemented in Smith Cart.  As a secondary measure, most payment gateways offer a duplicate transaction filter that can be configure to prevent duplicate transactions at the gateway.

If you are still having issues with customers submitting duplicate transactions you should look at performance of your site.  Make sure that your hosting plan has allocated enough bandwidth, CPU and RAM to properly run a dnn site and that your DNN portal is properly tuned for performance.

To improve response times there are a few items you can do to tune your dnn portal. Here is a good post on tuning http://www.mitchelsellers.com/blogs/a...

Also here are a couple other items for you to look into:

• You should have at least 2gb allocated to your web server
• Performance and tuning on your sql server
• Clear windows, iis and sql server logs including your DB for the portal. Large log files can cause poor performance

Who is your hosting provider?