Hi, I'm afraid navit on n810 is not super fast no matter what you do in the build. MY experience so far is that it's pretty good until you get an actual gps signal at which point responsiveness drops a lot.
I've been somewhat busy with other things so I've not had a chance to try much new recently.
I do have an RSS feed of the changes going into the code base which is shown on my blog
http://danielwould.wordpress.com
I have been keeping an eye out for interesting looking changes.
As for the 5 star rating, it depends what you want from the app, it continues to have great potential, and is really nice for rendering maps of the area you're in, if what you want is to keep an update map of your country and be able to render your local area without an internet connect etc, then it is fantastic. However navigation remains slow. ( too slow for me, but then I have a tom tom and sat nav on my phone so I have a low threshold for switching if I just want navigation that works)

If I get time this weekend I might finish what I started setting up scratchbox on my server, which at least puts me in a better position to try things.
Unfortunately Gerrit is the man that knows he C, so was better placed to actually make improvements ;-(


UPDATE: taking a look today there have been some updates around gypsy as an alternative to gpsd. It seems gypsy is going to be used in fremantle and I'm investigating what I need to do to try things out on the n810. I have no idea if it will have a performance benefit. If anyone else knows anything about gypsy, installing/configuring etc. please post about it.