During an optimisation cycle for Bazarooma aimed at further reducing latencies I started experimenting with Firefox’ HTTP pipelining [1] feature, which is disabled by default. This can be enabled by typing about:config in the URL bar, locating the network.http.pipelining entry and setting it to true. While Firebug did not report any measurable improvement, it turned out that the wrong resoures were randomly returned for certain requests. I.e. a request for a JSON document would return an JPEG image, images would get mixed up and even the home page would occasionally be substituted for other resources.
To make things more interesting, this did not happen when a Varnish reverse proxy was inserted between the browser and the webserver. Unfortunately I’ve never established on which side the problem lies, but pipelining needs to stay off for now.
[1] Wikipedia article on HTTP pipelining
http://en.wikipedia.org/wiki/Http_pipelining
George's Techblog 