reverse proxy and "real time" applications

I have a bunch of (intranet) web applications which are running behind an apache reverse proxy (PoxyPass / ProxyPassReverse), this is done purely as a handy abstraction - security, Apache performance or any other such thing doesn't really play into this (they are long running / resource intensive scripts with relatively few requests).

The problem that I am having is that for some of these applications I like to keep the HTTP connection open for extended periods of time to continuosly provide updates (counters, progress bars, that sort of thing) for the entire duration of the process, which can be hours in some cases.

When I try this through the proxy, it waits until it gets the entire response before sending it to the client (and many cases times out).

Any ideas on an approach to fixing this?