Argh! After reading carefully the description of the 1005, I saw that entry about plugins and rsp.so. The make install doesn’t copy rsp.so to the place and there is no default entry (logically) in the conf template. So now I serve rsp and displaying all >7100 titles is down from 40 seconds to 4 seconds. Was minutes on Twonky :P.
The other questions remain, maybe you have a hint: Sampler and Artist/Album, how shall I proceed?