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Strange performance discrepancy with proxy

From: Matt Kunze <>
Date: Wed, 13 Mar 2013 09:17:47 -0600

We have recently integrated libcurl into our application to provide the
underlying HTTP transport (replacing WinINET, which is a huge improvement,
thanks!). The application is using the multi interface, though for the most
part on a single request is made at a given time.

I'm seeing strange behavior where requests are _much_ faster when routed
through a proxy (in this case the Fiddler diagnostic tool). Note that this
not a caching proxy, and all the requests are POSTs anyway, so I don't
that is the explanation. If I run the app with an HTTP_PROXY environment
variable defined it is much faster than without - the code is the same in
cases. I've instrumented the code as well to display the progression of
requests, and it appears to be the same in both cases except the proxied
requests return much faster.

I'd love to have the same performance regardless of whether or not a proxy
used, so is there something I'm potentially missing that might speed up the
non- proxied case as well?



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Received on 2013-03-13