I have found that depending on which version of IGO and the version of the maps you are using, the setting of the cache and
reserve_memory settings in sys.txt makes a big difference in performance. If you get slow video, with flashing green/white colors on your unit and then "out of memory error" , I found that you have adjust the above mentioned settings. Thru expermentation I have found that if you increase the cache it will improve video performance (eliminating the white/green flashing) but increasing it too much will give you a errors in route recalculations while driving. IF you increase the reserve_memory, you will speed up route calculations, but the program itself seems to run slower. I am not a programmer, so this is all from experimentation. I still occasionally get "out of memory errors" with this sys.txt, but it seems pretty good for what I am running. Igo 8.3.4.102680, NavTeq 2009.03, with the Kikker 3.2 skin. This is my sys.txt, if you have found a better combo please post. All poi s have been turned off, except for Speed cameras, and speed traps.
[device]
type="nextg828"
[debug]
enable_roadshadow=1
show_residentonly=1
enable_roadsign=1
enable_landmark_occlusion=1
show_oneway_3d=1
show_oneway=1
show_gps_pos=1
show_signpost=1
background_navigation=1
screen_calibration=1
skip_eula=1
no_file_cache="1"
cache=5096
reserve_memory=500000
[map]
3d_max_tiltlevel=9000
stop_rotate_on_map_move=1
inertia_on_map_move=1
follow_gps=1
2dheadup=1
[poi]
poi_show_all_btn=1
poi_labels=1
show_poi_boundingrects=1
show_poi_areas=1
[navigation]
show_current_city=1
show_countrychange=1
autoreplan_action="AUTO"
gps_pos_to_road=1
sim_speed_factor=3.0
[timezone]
patch_dst=1
[timezones]
use_timezone_setting_fix=1
use_new_timezone_ini=1
timezone_key="Time Zones"
[3d_config]
disable_roadsign_navigation_mode=0
[interface]
maxzoom2d=6000000
show_exit=1
[sound]
use_method=1
queue_length=200
[tts]
tts_buffer=131072
tts_logics=3
priority="HIGH"
always_say_road_names=1
announce_street_name=1
announce_exit_directions=1
skip_exit_numbers=0
[rawdisplay]
gx_force_using_dll=1