Hello Matt,
The performance levels are the levels that appear as a badge on the pages of each package.
Usually you can execute certain missions to move on in the current level. Then you can move on to the next level when you complete all the missions of the current level.
If you go to your author page, you can find a link to the mission progress status pages. In that page you can see the performance level you are now and how many missions remain to move on to the next level.
phpclasses.org/status/