Right, we're not doing an compression. I don't think it would make sense in this context. The archive file will already be compressed in the app zip file, and I don't really want to spend the time to decompress the 5MB file in Dart. Right now, the only part of the archive that has to be touched when opening the SDK is the header - currently about 200 entries and about 10kb. The rest of the archive's contents are only accessed on demand.

Once we do have something like a native zip decoder, it might makes sense to move the archive format over to that (w/ a 0 compression level).