In a word: Yes.
Although "Hey, use a profiler!" might be good advice, it's not on-topic or sufficient for this site. This site is for Code Reviews, and an answer on this site is not on-topic if it refuses to review the code.
Instead of being posted as an answer:
- It can be posted as a helpful comment to the question
- It can be a vote to close the question (if the question doesn't contain code which can be reviewed)
Another example is:
- Here I wanted to mention some links to other algorithms, but I didn't want to review the OP code: so I posted that as a comment, not an answer.
- Here I also posted a link to other algorithms, but I also reviewed the code: so I posted that as an answer.
My policy is similar to the one in this meta-answer regarding answers which contain code, i.e. "Could this answer have been written by reading the text which describes the problem, without reading any of the code in the OP?"
- Yes, not one word of the answer relates to any word in the code of the OP -- therefore it's not a code review and is off-topic: "It was posted as an answer but does not attempt to answer the question (i.e. a request for a code review1). It should possibly be a comment ..."
- No, at least one word of the answer relates to the code (not just the description of the problem) -- therefore it's a code review and is on-topic.
1We know the question must have been asking for a code review, otherwise the question wouldn't have been on-topic.