It also depends which SPDY features you want to take advantage of. SPDY has content push support, for example, so if you're serving a page and know which asset

It also depends which SPDY features you want to take advantage of. SPDY has content push support, for example, so if you're serving a page and know which assets it will require, you can serve those without waiting for the client to receive your initial response and request them. So far as I know, the nginx SPDY proxy doesn't try to do any of this (and it probably doesn't make sense for it to do so).