To improve application performance in OutSystems, there are several things you can do. First, for API performance, make sure to limit the amount of data being returned and reduce how often external API calls are made. You can also use caching to avoid repeating the same requests. For managing role access, simplify permission checks and centralize them. When dealing with large data, use pagination to load only what is needed, and optimize SQL queries for faster results. You can also handle heavy tasks asynchronously, so the user interface doesn’t get slowed down. For security, use OAuth or JWT tokens to manage authentication and consider Single Sign-On (SSO) to reduce the load on your system. 

While these are helpful steps, they are not enough on their own. You also need to think about things like database optimization, improving front-end performance, setting up proper logging, and making sure your network infrastructure is efficient. 

Lastly, it’s important to regularly monitor your application’s performance and make changes as needed to keep meeting your performance goals.