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Re: Poor HTTP POST upload performance

From: Daniel Stenberg <>
Date: Wed, 15 Apr 2015 20:41:16 +0200 (CEST)

On Mon, 13 Apr 2015, Bryan Christ wrote:

> I've been trying to figure out why http POST uploads are so slow with
> libcurl. Upload speeds continually perform at about 1/10th of the expected
> performance (or less). Many users have reported this behavior on our forum.
> I suspect it has a lot to do with CURL_MAX_WRITE_SIZE being set to 16k.

Why suspect? Rebuild a test version with it set to 1024KB and see what
difference it makes (if any) and remove any doubts.

We have settled on the current size only because we have not seen any evidence
of a larger buffer giving any notable difference (in most cases - not counting

We are always open to reevaluating our former decisions, but we prefer doing
so based on data and evidence to back up the ideas!

I suspect you see less than expected transfer rates because of something else
so I'll second the request for a stand-alone app that shows such a bad

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Received on 2015-04-15