Performa is an energy source in Tokyo Mirage Sessions ♯FE.
Performa is the latent creative energy within a person. This ranges from any sort of thoughts and drives related to creative arts such as acting, singing, dancing, or similar pursuits. Individuals have varying levels of Performa in them with particularly creative people having stronger Performa.
This energy source is deeply associated with the Idolasphere and the Mirages that dwell there. Mirages can turn hostile and siphon Performa from humans. The sudden loss of Performa leads to despair and extreme lethargy. If a person's Performa is devoured entirely, the person would die.
A select few humans contain so much Performa that they can actively resist Mirages from draining it. They can use their Performa to purify malevolent Mirages and bond with them, granting them a fused power called Carnage Form, allowing them to fight other Mirages.