AppNap is a feature in Mac that helps to maximize battery life. However, it may causes issues with the Citrix. Citrix Receiver is required to access all Design Manager Cloud and SkyBox applications.
To prevent these issues, disable AppNap for Citrix Receiver.
- Go to Finder
- Go to Applications
- Right click or Control+Click or Cmd+Click on Citrix Receiver
- Click on Get Info
- Check off “Prevent App Nap”
Source: http://www.tips-and-tricks-in-mavericks.com/disable-app-nap-on-a-per-app-basis-in-os-x-mavericks/