Learn English – Which is more grammatically correct – “performance in” or “performance on”

Performance really depends on the object: You perform IN a play but you perform ON a stage so:

His performance in the play was enjoyable.

His performance on the stage was enjoyable.

So really your question comes down to: do you perform on a test? Do you perform in a test? I would lead towards "on" because of other usage:

His grade on the test was 90%.

Your third answer on the test was incorrect.

Then again, if we are really talking about an implied "performance in taking" the test, suddenly this could be correct:

 John's performance in (taking) the test shocked the teacher.

However I would also go ahead and call both of them "awkward". I would avoid entirely and use

John's performance during the test shocked the teacher.

Or best of all, use K.I.S.S. and avoid the problem altogether:

 John's test performance shocked the teacher.