1. Map overlay results in at least doubling the CPU and mem load and makes it unuseable completely, the system slows down and just a big problem... You've already mentioned you're working on this. 2. Same with autorotation, to a lesser degree, it's useable but slows it down considerably. But that's how a nav should work, so this feature is needed. I understand you're also already addressing this issue.
3. This one I think is critical - the tile loading is still a SUPER slow process. It is slightly better when using the sql than regular files. The speed of loading each individual tile for display seems to vary, however in extended navigation it howers somewhere slightly under 2 secs per tile. This is terrible, since usually you're displaying a screen of 8 tiles or so, they go from green to display (this is for already downloaded tiles) one by one, each in under 2 seconds. The whole display thus takes 15 seconds, this on zoom in and zoom out, so this problem is a significant one.
It seems to me that tiles are also loaded around the visible area of the screen, since when dragged they are showed immediately for a while.
However there is some intense processing when loading the tiles, which results in this incredibly slow loading process, which is bad. Finally, I strongly recommend making the tile download also LIFO, as it's FIFO I think, and it's a big prob when on the move, zoomed in, downloading new tiles. It should be LIFO just like tile loading, with the ones no longer needed download paused and resumed after the visible ones are downloaded.
Another quite big problem is the size of the font. Many times, as has been mentioned here before, it gets messed up and is SUPER tiny, meaning you cannot read it. This issue usually corrects itself with the move to next driving direction, however it's always on a specific direction, i.e. if it's tiny, you go to next which is big for instance, and then back to the tiny one, it stays tiny. More often than not, the directions' font is tiny which is a big problem, since many times I wanted to check the km to next turn etc. but couldn't.
Also, you definitely should change the setting for distance when speaking the directions to time-based interval setting, i.e. how many secs before a turn based on recent speed. I also recommend adding, total remaining distance towards goal in the directions blue window display, not only next turn, but total remaining km.
These are my major remarks in testing the latest version.
Thanks for the big improvement, and please try to focus the tile loading especially, as well as considering my other suggestions.