The antonyms for the term "more performable" are limited, inflexible, unadaptable, and unmanageable. Limited refers to something that is restricted or has a small scope, making it difficult to perform or execute. Inflexible denotes a lack of adaptability or changeability, which may hinder performance in certain situations. Unadaptable refers to something that cannot be modified or adjusted to suit different circumstances, making it challenging to perform in varied scenarios. Lastly, unmanageable suggests something that is too difficult, complex, or unruly to perform well. In contrast to the word "more performable," these antonyms indicate a lower level of suitability or ease of execution.