Slowness in opening JPGs

Discussion in 'Digital Cameras' started by Terry Pinnell, May 23, 2005.

  1. When I open a JPG file (50-200KB) in IrfanView and then 'browse'
    through the rest of the folder's images using the arrow tools (or
    keys), each image opens rapidly. But if instead I d-click individual
    JPGs from a My Computer folder, *sometimes* the first one opens
    quickly (I have JPG associated with IrfanView), but then subsequent
    openings can take up to 5 secs. The odd thing is that on other
    occasions I can open the same images successively and *all* open
    quickly. This can be within 5 minutes.

    Anyone able to suggest possible causes please?
     
    Terry Pinnell, May 23, 2005
    #1
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  2. Terry Pinnell

    ASAAR Guest

    When you browse through successive jpg files in the same folder,
    you don't have the delays because Windows has already pre-read the
    directory contents of that folder, and has all or most of it
    buffered in memory for quick access. I'm not sure what you mean by
    a "My Computer" folder. Is that a folder you've created on the
    Desktop? Check the properties of the icons in the folder that
    represent the JPG files. If there's only a "General" tab, then the
    actual JPG files is stored in the folder. These will be able to be
    accessed quickly. But if the icon's properties shows a second
    "Shortcut" tab, then the folder only contains a .LNK file, and the
    actual .JPG is in another folder. Each time you try to open one of
    these "jpg" .LNK files, if the actual .JPG file is in a directory
    that hasn't been accessed recently, then before Irfanview can open
    the file for viewing, Windows will have to pre-read a certain amount
    of the directory entries for that folder. Depending on many
    factors, such as the hardware used, the number of files in the
    subdirectories, the available system memory, the state of your
    computer's virtual memory, whether other tasks are running
    (especially if they're using the hard drive) etc., the pre-reading
    of each folder's directory entries might be very quick or produce a
    noticeable delay.
     
    ASAAR, May 23, 2005
    #2
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  3. A 'My Computer' folder is the single-pane variant of an Explorer
    folder - the type I always use. Here's an example of each:
    http://www.terrypin.dial.pipex.com/Images/Folders.gif
    Thanks, but these are plain JPG files, not links.
     
    Terry Pinnell, May 23, 2005
    #3
  4. Terry Pinnell

    ASAAR Guest

    Then the only thing I can think of is that you've got a very
    active computer system, copying, moving, or downloading files. I
    notice on my own computer that if it had been busy and then all
    activity stopped (such as if while downloading unattended, the
    connection to the internet was broken), there would be moderately
    long delays several hours later if ANY operation was attempted that
    required even the smallest amount of disk I/O. This would include
    not only attempting to view small JPG files, but even switching from
    one resident app. to another. In particular, Agent's redrawing of
    the screen when you switch to it, or even scroll slightly through
    the message list requires disk I/O. Presumably when this is
    attempted, Windows wakes up and says "OK, but I've got to reorganize
    my virtual memory first . . ." or something like that, and before
    anything changes on the screen there's a substantial delay, usually,
    but not always preceded by lots of disk activity. When delays
    aren't accompanied by disk I/O, I assume that Windows is doing a lot
    of housecleaning or rearranging the contents of its memory resident
    registry, which is rather bloated, being about 5 or 6MB larger than
    it was several years ago. It could be something else entirely
    that's responsible, but that's my current theory. :)

    Your problem with the JPG files might also be due to something
    else. You don't happen to have several hundred or more JPG files in
    the folder, do you?
     
    ASAAR, May 23, 2005
    #4
  5. Thanks for the follow-up. I reckon your theory has the ring of truth.
    I do have quite a lot going on usually when opening such files. (This
    particular folder BTW has about 200 JPGs in it, average size 300KB.)
    And, despite recent attempts to cull it and optimise it (with
    NTRegOpt), my registry is also very large (56MB total).

    Yet if IrfanView can open each full image so quickly when I'm in its
    'Thumbnails' browsing mode, intuitively it seems strange that Explorer
    is sometimes so glacial. And, of course, that 'sometimes' implies
    there are plainly background operations occurring only *some* of the
    time!

    I may try to fire up a handy utility I have called Filemon (do you
    know of it?) and see if it can tell me what other activities are
    occurring when this slowness arises. Trouble is, from pervious
    experience, Filemon shows a truly daunting list of activities, even
    when the PC is apparently idling. So detective work can be impossible!
     
    Terry Pinnell, May 24, 2005
    #5
  6. Does Windows show thumbnails for the files in the folder? If it is
    generating thumbnails in the background it would probably slow things
    down, probably from memory usage as much as CPU. I am not sure exactly
    how Windows generates and manages thumbnails.

    After it had finished generating thumbnails for all the files it would
    work at normal speed. Is it slow when you first open a folder, but
    fast if you have had the folder open a while?
     
    Andrew Rowley, May 24, 2005
    #6
  7. This slowness occurs whatever view I'm using, Thumbnails, List or
    Detail. (And if I'm in Thumbnail view, I wouldn't attempt opening an
    image until all thumbnails were finished.)

    For example, after reading your post I re-opened the folder in List
    view. I d-clicked the first of 200 or so JPGs, Image1, and that opened
    rapidly in IrfanView. I closed that image, and d-clicked the next on
    in my folder, Image2. That took just over 4 seconds to open. I came
    back here to type this.

    OK, hang on, now I'll try a few more. The first one I opened was
    Image1: about 1 sec - not as rapid as initially. Next, I repeated
    Image2: about 1 sec, faster than before
    Image 3: about 1 sec
    Image 4; just over 5 secs.
    No pattern at all!
     
    Terry Pinnell, May 24, 2005
    #7
  8. Terry Pinnell

    ASAAR Guest

    What I was wondering when I asked how many jpg files you had in
    the folder was that Windows probably doesn't buffer ALL of the
    directory entries it encounters, only the Most Recently Used ones.
    Just because you see a screenful of jpg files in List View, they
    probably aren't sorted in the same order that the directory entries
    occur physically on the hard drive. So if you click on two or three
    and they happen to be close enough to be in the same block of
    directory entries that's being buffered, IrfanView can open them
    with minimal delay. But if you try opening another jpg file whose
    directory entry is distant, and therefore may not still be buffered
    with the rest of the jpg directory entries, then Windows will have
    to return to the hard drive to learn where this jpg file is located,
    incurring a delay. If you create fresh directories and copy a small
    number of jpg files to them, such as 10 to 20, it would be
    interesting to see if you ever see occasional delays accessing any
    of the files after viewing the first one.
     
    ASAAR, May 24, 2005
    #8
  9. Terry Pinnell

    Ron Hunter Guest

    Irfanview will read in the next picture, and begin processing it for
    display, so it can seem very fast. However, the size of each picture,
    and the fragmentation level of the HD can have a great effect on how
    fast it does this job. There is also the issue of other tasks running,
    the speed of your CPU and RAM (and HD), and where your swapfile resides.
    There is NO need to close one picture in Irfanview before displaying
    another, just click on the arrows on the toolbar.
     
    Ron Hunter, May 24, 2005
    #9
  10. Thanks, but I think you misunderstood. I'm making a comparison with
    the speed of opening in IrfanView's browse mode. The slowness under
    discussion here is when opening by d-clicking from Windows folders,
    not in IV. As described in my first post, I open successive images in
    IrfanView's Thumbnails (browse) mode "using the arrow tools (or
    keys)..."
     
    Terry Pinnell, May 24, 2005
    #10
  11. Thanks for your continuing interest in this puzzle. But I didn't
    really follow your rationale. In IrfanView the speed of opening is
    consistently rapid, no matter whereabouts in the folder I start and no
    matter how many successive images I open, right up to the extremes at
    either end. Anyway, I don't think the order of the files should really
    make this large difference (a fraction of a second in IV to 5-6
    seconds from a Windows folder) . But I did try your suggestion. I made
    a new folder and dragged 10 of the images into it. Same behaviour as
    before. (I tried a couple of locations for the test folder too.)

    BTW, I defrag my HD every day or two.
     
    Terry Pinnell, May 24, 2005
    #11
  12. Terry Pinnell

    ASAAR Guest

    You weren't clear enough in saying "Same behaviour". I don't know
    if you're talking about IrfanView's behaviour (files open quickly)
    or double clicking from a Windows folder (most quickly, a few with
    delays). My assumption (not necessarily correct) was that with only
    a small number of files in the folder, you wouldn't see longer
    delays when double clicking on successive JPGs, no matter how the
    files were ordered. IrfanView uses an alphabetical sort, and unless
    the JPG files were randomly named, this is usually consistent with
    the order that the directory entries were created. Windows folders
    are more flexible in their sort order. Are yours also sorted by
    filename, or perhaps by size, date, etc. If they're sorted
    similarly to the way IrfanView's sort order then the answer to your
    puzzle lies somewhere else. Have you tried double clicking from an
    app. such as Windows Explorer or one of its replacements such as
    Powerdesk, etc.?
     
    ASAAR, May 24, 2005
    #12
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