Indicates whether the current String object is is participating in a fast pass operation. In a fast pass operation, reference counting is suspended.
true if the current String object is fast-past; otherwise, false.
In a call to a function where a reference-counted object is a parameter, and the called function only reads that object, the compiler can safely suspend reference counting and improve calling performance. There is nothing useful that your code can do with this property. The system handles all the details.
Minimum supported client: Windows 8
Minimum supported server: Windows Server 2012