Hi, not sure if I found a bug:
When in the range of the slot indicates a busy year earlier, in my case proved 1753 (First year sql server). Schedule performance drops significantly.
Slot slot = this.CreateWorkingSlot(new DateTime(1753, 1, 1, 9, 0, 0), new DateTime(1753, 1, 1, 13, 0, 0), RecurrenceDays.Monday | RecurrenceDays.Tuesday | RecurrenceDays.Wednesday | RecurrenceDays.Thursday | RecurrenceDays.Tuesday);
I'm afraid you do a loop in reverse.
Sorry for my english and thanks,