It's their copyright, they get to decide the conditions in the license if you want to use their software.
The EULA is enforceable because you have to agree to it to use the software, and Oracle has large and well financed legal team who will descend from a great height on you and anyone who publishes the results of you doing performance testing.
That doesn't address the question of the limits of what should be enforceable in an EULA
Only to the point it doesn't infringe on your statutory rights.
In the EU (and still the UK since they've not changed the law since) you have the right to benchmark software.
However, it doesn't include the right to publish the results, so you can only do it internally for Oracle and any software that has similar clauses.