TomTomXL in constant recalculation

[wlepse]

A while back I picked up a TT XL for my parents after they used my old TTOne and really liked the added piece of mind. They have been using it now for about a year without much in the way of problems. But recently they just took a long road trip (750 miles) and I ended up getting a call from them since they got lost in DC and the device was no longer talking to them. I gave tehm directions to get back but they said the whole way they didn't have any voice prompts. So I picked up the unit to check it out and immediately found that the voice prompts were working! Now much of what they tell me I have to take with a grain of salt because they are far from techies but I did find a problem as I continued to drive. If I missed a turn it takes a really long time to recalculate. I tried shutting off IQ routes but that didn't seem to make much if any difference. I think the issue is related to the length of trip. Previously they only used it for 50 mile or so trips, this one was 800. So this morning I set my One and this XL to route me on the same trip and was surprised to find the One was ready faster and recovered from missed turns faster. I also found that if I missed more than 4 redirects on the XL it seemed to lock into recalculation and not advance until the car stopped. Is this normal for this device? Why would a significantly older and less advanced unit run faster and better? Any ideas on what to try?