I have now done some of Cottenham with Donald, a few tweaks in Ealing and a start on Great Gransden.

Obviously I'd like to see how the maps are rendered. There are various quirks in this area of course.

From the users' point of view OSM has a few obvious failings.

The search is horribly horribly slow. Why is this so ? Is somebody doing this or is there a position available ?

I have read somewhere that tiles that appear as "...more OSM coming soon" mean that a tile is being re-rendered.

What is wrong with displaying old tiles until their replacements are ready ?
If that cannot be done would it be wrong for the text to say "tile being rendered" instead ?

For user-facing layers displaying this text instead of a tile is wrong.

At the time of writing c.tile.openstreetmap.org is sick . In fact a typical tile requests produce the 3 byte text "nil" still with a Content-type of image/png so that's not right.

It looks like [abcd].tile.openstreetmap.org are the same machine and this seems to be a valid technique for making browsers request more in parallel (in the absence of pipelining) as they only do a few per hostname.

More generally I am interested in the policy for encouraging http cache-ability, while propagating updates when they are available at the same time as tracking the tiles of interest.