OK, something fishy is definitely going on... I did uncheck the 'redraw once new tile is loaded' option, and then: it seems modrana still gets stuck, in a funny way... The cursor position, and the blue box with directions would disappear for 10-20 seconds at a time, while the underlying map, with the traced route is visible... Anyhow the cursor and blue box would flicker on for a split second, only during this time, if you'd touch the screen, I could access the menu.
It is apparent that gpsd is not the hog though, since once I'd get in the menu, I could flip through options and nothing would get stuck, though gpsd is clearly still running in the background. Once out in the map though, it'd get stuck again. Tried to display the tile load times in terminal, that's when I noticed some python cairo errors coming up in the terminal.
Anyhow, couldn't capture these, as my drive just ended. Said something about impossible rotation though or something. I'll capture the full errors in the morning and post. Could it be, that there's some python/cairo mess-up going on and due to this the display is getting stuck?