In florida, you get a certificate of completion if you can't pass the FCAT which is a standardized test. I know many people who applied with just that. On the USCIS website the guidelines say that:
6. Are currently in school, have graduated or obtained a certificate of completion from high school, have obtained a general education development (GED) certificate, or are an honorably discharged veteran of the Coast Guard or Armed Forces of the United States.
Maybe your certificate of perfomance is equivalent to a certificate of completion. However, I am not sure. You should ask your school if the certificate you received is like a certificate of completion.