yeah, working with the whole package is not ok. my latest idea is this: upload all parts as single file in some server where you can query single parts. Then in javascript i scan an ldr/mpd and for any reference to a subpart, i query the server to obtain it, and use all the parts to build the full geometry.
This would allow displaying of arbitrary models (ie embeddable in html, from user textarea, etc) without any server side work, with hopefully minimal bandwidth usage. I've tested that my Viper model uses about 80 parts for about 300kB total, which can be compressed to about 30kB with gzip, quite good. With this performances is more easily to overload the video card than to use too much bandwidth :)
The only problem is that it would generate 80 asynchronous request to the server, which can be quite a lot. But parts file are cacheable so that should help.
I'll try asap