Improve the performance of an existing web application

General information for the business: Healthcare Audit Tool
Kind of development: Customization of existing program
Description of every module: We have developed an online hospital ward audit tool but it has become very slow. It has been developed using ".NET" with boo strap and the back end is SQL server. The system is hosted in the cloud.
Description of requirements/functionality: I want someone to look into the application and let me know where the issue is and a quote to improve the performance of the system. Currently, it takes about 12 -20 seconds based on a number of users in the system to save one set of audit details (this mean one click on save button and wait for 20 seconds to save the data). I know it's not just saving, ut has to do lots of checks before saving the data but 12 seconds is too much. I would expect it to be at least 1 or 2 seconds.

The demo site can be accessed through www.healthkpi.net/ward_audit and select "Login as Guest". The issue is in the data entry page.
OS requirements: Windows
Extra notes: