Well, if it's a TT GO then it's got a 320x240 display, which is way easier to drive than the N800's 800x480 display.. there are 5 times as many pixels in the latter. But it could also be a question of how good/optimized the navicore software is. This is the 770 version I assume. (In any case one must realize that TT is possibly the top contender to compare with, it _is_ very smooth. Runs like hot butter on my 480x320 Palm T3. I checked out a built-in expensive-looking navigation system in a fancy car, and it was crude and jerky compared with TT.)

In any case it's also true that most GPS (at least the NMEA ones) updates just once per second, as was said already by jpj.