[debian] navit: rendering is slow

[arne anka]

i enabled the small screen gui ("internal" it is called, i think) and  
tried out navigation.
so far rendering is _very_ slow and the cpu usage applet always shows  
about 80-100% usage -- thus eating power quite fast, i presume.
it takes a long while (and someinteraktion) to make the current map to  
appear, even after gps obtained a fix i had to swith to some dilog and  
back to the map view to make it rerender.
after the map was there and navigation hints appeared i made the  
matchbox-keyboard appear which took up the upper part of the screen. after  
disabling the keyboard the part of the navit window remained grey (though  
the window's top bar was redrawn immediately by xfce), after several  
minutes the small rectangles were redrawn -- but that was about all,  
navigation information ("turn in ... meters") seemed not related to my  
current position anymore and the map never was redrawn while the cpu usage  
was still exceptionally high.

after about 15min i killed navit.

navit is 0.1.0+svn-1791, built without speech, map is the eu.bin linked to  
in the navit wiki.

my questions so far:
- is navit's navigation usable at all on a device so limited? (other  
experiences?)
- is the high cpu usage rather a bug or an unavoidable side effect because  
of the fr's little mind?
- is there a tweak to make rendering more responsive (eg by rendering less  
detailed?)