Is getting the thread ID expensive in terms of performance?

Question

I need to access the thread ID from threads that I don\'t control (it\'s in an asynchronous callback function, and it get called from a set of different threads).

I

Answer 1

According to MSDN (DevDiv#1039430), prior to VS2015

this_thread::get_id() was unnecessarily slow

Just how slow they don't say.