I have been struggling with this issue forever. I am using my Google nav app and all of a sudden it freezes barely updating with CPU @100%. I have tried different options using 3g instead of 4g, not using bluetooth, not starting nav when CPU is busy nothing has worked. All of a sudden either at the start or during a navigation session the CPU will go up to 100% and the app will stop updating and if I am driving I left without directions until I reboot. Huge headache. I used different system monitors like 'WatchDog Lite' and 'System Tuner' and those apps say that the most CPU consuming process during that time period is 'Android System Process'. I have no clue as to what 'Android System Process' is doing during that period of time except it is taking a large amount of CPU.
Only option left is to overclock, upgrade to a faster CPU from Verizon or go to Apple IPhone