If you are reporting the SPI to the stakeholders, this is performance information.
Here is the thing. A measurement is a “value” that a project team determines, measures or calculates. Information is a measurement in a form that can be distributed to the stakeholders. Usually you transform the measurements into more understandable information.
Let me give you a real example. I work for an airport operator in the PMO department. We calculate all earned values for every capital project. So we do calculate the EV, CPI, TCPI, EAC etc. However, our stakeholders, other departmental heads and board of directors etc. do not understand this PMBOK jargon. On a monthly basis we have to transform these measures into more understandable (textual description) reports and send them across. So in this example, the EV measurements are the “measures” while the textual report is the “information”.
Please note that actual interpretation varies from organization to organization, and it very much depends upon the overall maturity of the organization. Let me know if this helps resolve your confusion.
Regards,
Khurram