OK, I ended up rooting my TB 3 days after I got it - way back when - because of the INSANE amount of time it took for my GPS to lock on my position. After rooting/ROMing I have been golden with my GPS locks and haven't looked back since.
However, a guy in the I.T. dept. here at work has a stock, unrooted TB with the most recent update (1.70.whatever.whocares) and he was still suffering from severe GPS lock issues (10+ minutes to lock). So, I advised him to let the GPS lock and then reboot the phone. Ever since doing that he has been getting instant GPS locks (3-5 seconds) in all different sections of town and even out of town. It has been several days since he has done this (and several reboots) and it's still locking on great! Needless to say he's pretty happy about this lol.
I have searched the forums and didn't come across this as a recommended solution so I thought I'd post to see if it works for anyone else experiencing the problem.
Hope this helps someone else!