[morecoffee]

> Tech Details

> The SPIF format starts with a header that tells the offsets and sizes of the images in the SPIF. The images are stored smallest first, but there are no image size restrictions apart from that.

So... two HTTP requests per image load? That is probably going to hurt more than it helps. Also, that probably means a Range request, which don't have great support. (For example, the builtin Python http server SimpleHTTPServer doesn't support them.)

[jsjohnst]

While I agree with your other point re: multiple round trips completely, the part about Range requests feels misplaced. Any "real" HTTP server that anyone would use for hosting images these days supports them. Yes, some simple developer tools may not, but it's not hard to add if there was value to.