Send head before body to load CSS and JS asap
Response.flush() at the end of the Masterpage
page_load, but the page layout is horribly broken afterward. I’ve seen a lot of people using an update panel to send the content using AJAX afterward but I don’t quite know what impact it would have on the SEO.
If I don’t find a solution I guess I’d have to go the reverse proxy route and find a way to invalidate the proxy cache when the pages content change.