The problem you are having is that the firmware probably did not upgrade correctly and you are now on an older version which is causing the issues you have having. We have retired the AudioBox VSL 1.3 software.
Please install Universal Control 1.8 (or higher) which will remove the AudioBox VSL software and update your 1818VSL to the latest firmware. This should resolve your performance issues.
Go to the product download page to get UC 1.8: http://www.presonus.com/support/downloads/AudioBox-1818VSL