Yep i've noticed it as well. Previous FW appered to work ok. Here is how mine appears..
I set the speed display on.
I set the display to auto dim.
Over the last few weeks the GPS Speed is taking at least 5 minutes in the morning to show any values. Initalliy 0 is shown and then some slow updates with eratic, sometimes wildly inaccurate, speeds shown. After it has settled down and I am travelling at a steady pace the GPS speed is mostly accurate and tracking the car speedo. The update rate is slow and lethargic and often shows a decreasing speed to 0 when I pull up and wait at a junction. The display never dimmed.
However this morning on the way to work I had the normal as described above but as I had nearly finished my daily commute the display dimmed and the speed reading became accurate and updated at a good rate like it used to. This to me indicates a bug in the FW.
Anyone tried flashing back to a previous level if possible to see the results and if so what would be the best one to go for?