Pando Media Booster before, then you probably haven't downloaded one of several free-to-play games. It's meant to improve download speeds and speed in streaming clients, but in practical terms it's frequently cited as a resource hog that cripples performance on many computers. Aion was one of the many games that used the program following its transition to free-to-play, complete with the usual complaints, but as of now, the game can be played without the booster.
As of this afternoon, the game can be downloaded directly from the master NCsoft launcher without using any third-party workarounds. If you had already downloaded and installed the game, you can feel free to safely shut down and uninstall Pando Media Booster without any impact on your gameplay. Considering the horror stories that have periodically circled around the program, Aion players will likely be happy to learn it's no longer associated with the game.
[Update: NCsoft has contact us to clarify that the removal of Pando Media Booster from Aion is only temporary: "We temporarily removed Pando Media Booster so that we can test a variety of server-side adjustments regarding download completion rates and further refine the service we provide our players. We will bring Pando Media Booster back once we've optimized our service to provide the best download rates possible." Sorry for the confusion!]