Hi,
When I want to speed up the draw rate on my phone I:
1. Click on the 3 bars for the menu,
2. click 'Configure map'
3. Scroll to the last item in the list which is 'Hide'
4. I tick several items -
Boundaries
Buildings
House Numbers
POI icons
POI labels
Underground objects
5. Click 'OK'
6. Use the back arrow to get back to the map display, and
7. Force a screen refresh by clicking on either the + or -
If you want to, you can also choose a different map 'display' such as 'Map Style' = 'LightRS'
You will have to do this for each mode of transport you want to see less details on - car, cycle, general, walking etc.. I use a different amount of detail for each navigation option.
Good luck, and hopefully this will sort out your problem.
Regards
Nick (Tallguy)