Usage with nginx

If you are using nginx as a webserver, it will try to buffer the response. So you'll want to disable this with a custom header:

header('X-Accel-Buffering: no');
# or with the Response class from Symfony
$response->headers->set('X-Accel-Buffering', 'no');

Alternatively, you can tweak the fastcgi cache parameters within nginx config.

See original issue.