17,057,594,037,927,937 * 2 seconds = 34,115,188,075,855,874 seconds = 480,793,563.27 years.
3μs when you get one or more correct or 3μs for each one correct?
If it is 3μs for each one correct. One could get the value of all the bytes by trying strings all the same and then calculating how many are that value. From there it would be a matter of determining the correct order.