In the past week, my iPhone client has been showing a significant amount of GPS lag. The car follows my car accurately, but up to 0.3 miles behind at times. In turn, my navigation prompts are coming much later than normal, causing confusion.
I know it's not simply a GPS limitation, because I used to get turn directions right on time, to the point where I could confirm that nodes were placed properly because I'd get the prompt right on them. It's something that's only started recently.
Could it be that too many cached map tiles are causing slowdown? If so, I could try reinstalling again, but I want to avoid having to reenter my favourites and settings if possible.