OSMRenderer
The OSMRenderer fetches the map directly from the OpenStreetMap server and thus needs no preprocessing. However, it cannot run on the client without an Internet connection.
It shares most of its codebase with the MapnikRenderer, differing only in the method of fetching the tiles: While the MapnikRenderer fetches the tiles from a precomputed file, the OSMRenderer fetches them from the OpenStreetMap server.
In addition to this a 50MB disk cache is used as well as a memory cache.
Choose the desired zoom levels. It is advisable to omit some to allow for quicker zooming.
Each zoom level is twice the size of the previous zoom level. For a conversion from pixel to meter consult the OpenStreetMap wiki.
