S_L_O_W downloads with Adobe Acrobat was Re: Information about a HP 13197 1K WCS for the HP 1000?

From: Patrick Rigney <patrick_at_evocative.com>
Date: Thu Nov 6 19:14:56 2003

> Last week I was having a LOT of trouble downloading PDF files from Al's
> website. Adobe Acrobat was taking about ten minutes just to open the first
> page and I couldn't get any pages beyond the first one. Erik
> suggested that
> I right click on the file and save it without opening Adobe Acrobat. I
> tried that and it worked MUCH better. However Al said that I
> should be able
> to open the PDF file with Acrobat and read it and then save it without any
> problems. That agrees with what I knew about PDFs. Anyway I've been
> wondering what was going on so today I typed "Why is Adobe Acrobat slow"
> into Google and I got some interesting results. I found LOTs of reviews of
> Acrobat version 6 that also complained about it being SO SLOW. Some of the
> reviewers suggesting sticking with Version 4. Following their advice I
> uninstalled my current version of Acrobat (ver 5.something) and then went
> to oldversions.com and downloaded version 4 and installed it. It
> works MUCH
> MUCH better!
>
> If you're having problems with Acrobat being slow. Try removing it and
> then installing version 4 and see if that helps. It works for me!

I generally avoid viewing Acrobat files from within my browser (that is,
using the Acrobat plugin) altogether. A lot of older PDFs aren't
"linearized". There is a subformat of the PDF specifications that includes
additional data structures and file construction rules so that a PDF file
can be optimally viewed over a slow (relative to a local hard disk) network
connection, with reduced need for random access within the file. PDFs are
basically a tree of objects, and the organization of that tree might be
convenient for construction and perfectly adequate for random access from a
hard disk, but needs to be rearranged (linearized) for efficient sequential
access. This helps the PDF plugin and similar utilities get that first page
up faster, and improve page-to-page navigation time when the file isn't
local. Otherwise, even the plugin may need to download the entire file
before it can be displayed.

Even linearized, however, the plugin can still only work most efficiently
when the web server from which the file is served is able to respond
properly to an HTTP request containing a byte range specification, and not
all of them do.

IIRC, Acrobat 4 does not linearize files when saving, nor does the
stand-alone PDFWriter print driver, so older files may be less than optimal
for viewing with the Acrobat Plugin. Acrobat Distiller v4 does
optimize/linearize, however, as does Acrobat v5, Distiller v5, and later
kin. V5 also provides a batch tool to optimize a group of files.

Either way, Erik's suggestion is spot on in my book. There's no way to tell
if a file on a web site is linearized, so I always just right-click-and-save
so I can view the file locally. Aside from the performance thing, the
Acrobat plugin frequently causes my browser to hang randomly and for reasons
unknown, so I just avoid it.

Patrick
Received on Thu Nov 06 2003 - 19:14:56 GMT