i found out the the current code in db_exec_lob (called by cr_write_content) uses ns_writefp to return the content of content_rep files that are saved in the file system. i think that this is rather inefficient, because it does not write a "last-modified" header and therefore it does not allow the browser to issue a conditional http request.
simply changing the current code to use ns_returnfile is better because then aolserver itself cares for the last-modified info and also processes the conditional client request. Requests to dynamic images in the content_rep can then be answered with 304 responses as well.
at my site i can already see the difference that makes in the server access log :)
