This page says: "When enabled, profiling has a minor effect on performance."

While this page says: "Because the database profiler can negatively impact performance, only enable profiling for strategic intervals and as minimally as possible on production systems."

Of course the full story is that "it depends".

The first link is more optimistic, and can be wrong in cases where the profiling level is high, and write throughput is high. I'd suggest we aired on the side of caution and consistency, and advise to use profiling sparingly in production environments.