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Re: [css4-images] First draft of css4-images, feedback requested

From: Andy Davies <dajdavies@gmail.com>
Date: Sun, 19 Aug 2012 10:11:04 +0100
Message-ID: <CABbusAJW0BkoVYFKZ8pBDvwaAiEHhB3Th8CFHZzU9cwkWqAsqQ@mail.gmail.com>
To: Sebastian Zartner <sebastianzartner@gmail.com>
Cc: www-style list <www-style@w3.org>, "Tab Atkins Jr." <jackalmage@gmail.com>
Argh... I'll try replying to the list this time...

On 19 Aug 2012 00:26, "Sebastian Zartner" <sebastianzartner@gmail.com>
> Though when it's about saving bandwidth it makes much more sense to
decide considering the actual file size rather than the image's resolution,
which can be easily fetched via HEAD requests. So in the example above
there would be three HEAD requests. The first one would response that the
Content-Length is 1000000, the second is 500000 and the third 150000 and
the user agent with the slow connection would choose the last one instead
of the first one.

I'd say it's about the user experience rather than saving bandwidth and
performing a HEAD request for each image would have a negative effect in it.

A TCP connection would be tied up for the duration of each request, when
they could be being used to retrieve content the user will actually see.

At mobile latencies: 1/3 + secs RTT, the delay of each request would slow
things further.

I'd guess the pre-fetcher would probably have problem with multiple HEAD
requests, and as the pre-fetcher has been responsible for a lot of
improvement in page load times, I think we need to avoid breaking it if we

Received on Sunday, 19 August 2012 09:11:31 UTC

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