I upped the baud rate and I am now getting U12.22. I was getting U11.73 before so I gained U.49. I am pretty happy with that 
Read my post above That change has nothing to do with the baud rate.
Increasing the baud rate from 9600 to 115200 will remove a delay of roughly 50ms per nonce range.
(and that's also assuming that it was running at 9600baud and is now running at 115200baud)
A nonce range takes about 5.16s so that's about ... 1% ... (your change is 5% so clearly unrelated)
Again, U: doesn't mean much unless you've been running for a few days
After an hour it will be within about 10% of the final figure