We recently had a production incident which required enabling some off-by-default performance counters (http://msdn.microsoft.com/en-us/library/ms254503(v=vs.110).aspx) to help diagnose.
I was wondering if leaving these counters enabled would cause performance degradation?
The answers in What is the performance hit of Performance Counters seem to imply that the counters have a very negligible effect, but they make no reference to the 'off-by-default' counters.
If these counters don't carry a performance hit, then why are they off-by-default?