Start Render Time

[pmeenan]

Since you control the servers the only reason NOT to do it would be if you need to be able to modify the response headers later in the page (setting cookies, etc) since that becomes unavailable once you flush.

Stoyan has a little bit of a write-up with a few things to check here: http://www.phpied.com/progressive-render...e-flushes/

It could be that a lot of people disabled deflate and used php's output buffering to do the gzip compression (when they couldn't get it working on shared hosting).