Thanks @donmccurdy
You are using fflate which does converts ASCII to binary as far as I know.
USDZ is, according to my knowledge, a binary (zipped / gzip) USD.
Even for the use case you have mentioned, you are still loading 130 MB to the RAM.
Even if the output was ASCII I would expect to see the same difference like you would between a glTF and a GLB .
BTW, for the “on the fly” use case to work you will need the file (a blob link?) to have a curtain content type header - Content-Type: model/vnd.usd+zip.
Can you even do that with createObjectURL?