I have a rendering problem on the Samsung Galaxy 8 (1280x800). it happens that after some pinch-zoom actions, the display animation lags strongly behind. Thats means even if I don't touch the screen anymore, the map is still zooming and moving around for a coupled of seconds. Meanwhile, the program doesn't react to any further input and I have to wait till the end of the animation.
It doesn't sound typical for Navigator. Sounds more your phone is too busy to proceed. Did you check whether other RAM consuming apps are running at the same time?