Hi Fernando! The first sentence implies that the performance was, without a doubt, the *best* of *all* the performances. (You are comparing the performance to the rest of them.) The second sentence sounds very formal to my ears. Instead, I would probably say, "The performance was wonderful/great/excellent."

If you say, "the performance was the most enjoyable", then we need more context to know the group in question e.g. the performance was the most enjoyable one I have ever seen the performance was the most enjoyable experience I have had for a long time [The context could also come from a preceding sentence.] If you say, "the performance was most enjoyable", it is just a formal way of saying "the performance was very enjoyable".