Intermittent slow downloads of PDFs - InstantKB

InstantKB Problem
Hello - we are running InstantKB 2.06 and saving PDF attachments in our SQL database so they can be accessed using Full Text Search with the pdf iFilter.

We have intermittent reports from users of slow and failed downloads of PDFs. The PDF files range in size from 3.5 to 10 MB.

In a small test I've seen widely varying download times. A 6 MB file took over two minutes to download to my work PC at 5 PM but only 42 seconds to a home PC at 10 PM.

Can anybody comment on whether they have seen this and if there are known/possible causes? So far I've heard of cache settings in browsers that can interfere. It also sounds like download throttling mechanisms - such as used here to manage our bandwidth - can have an effect. What about other issues? Does it make a difference if more than one person is trying to download the same file? Are there web server settings that can come into play? Settings in the SQL db?

Any known issues and solutions are appreciated - thank you!
InstantKB Problem

FYI - our network administrator says he has seen reports that http compression, which we enabled on our web server a few months ago, can have the unwanted effect of slowing down PDF downloads and causing reports of corrupted PDF files.  We have disabled compression while we look into this.  Has anyone else heard similar reports?

Hi Alex, 

Hope your very well. Good question.

I would try fiddler to check the response.headers to see if GZIP is being used. If you see GZIP in the headers this indicates HTTP compression may be enabled within IIS and this can cause problems with steaming PDFS. You may see corrupted PDFs due to the compression. 

Can you try to disable HTTP 1.1  in Internet Explorer, which should also disable HTTP Compression support. You can get to this from Tools > Internet Options > Advanced > HTTP 1.1 Settings > Use HTTP 1.1. Ensure this is unticked. 

Please let me know if this helps Alex.
Kindest Regards,

Ryan Healey
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