I've committed some changes yesterday for KDE 4.11 that change the way we determine expensive information (like previews/mime type/icons/etc.):

https://git.reviewboard.kde.org/r/110839/

After this change, we no longer try to load this information for all items, but only for the visible ones, those which are close to the visible area, and those that can be reached quickly by pressing Home/End (at most 500). This means that the CPU will no longer be kept busy for a long time after opening a folder (unless you use "Sort by type" or sort by something else that leaves us no choice but to retrieve that information for all items).

However, if I understand your last message correctly, you say that it takes 5 seconds until you actually see the folder contents in the view, right? I'm not sure how much we can do about that in Dolphin itself, but it would be interesting to know how many items are inside that folder and what the files are sorted by. Thanks.

freininghaus wrote:I've committed some changes yesterday for KDE 4.11 that change the way we determine expensive information (like previews/mime type/icons/etc.):

https://git.reviewboard.kde.org/r/110839/

After this change, we no longer try to load this information for all items, but only for the visible ones, those which are close to the visible area, and those that can be reached quickly by pressing Home/End (at most 500). This means that the CPU will no longer be kept busy for a long time after opening a folder (unless you use "Sort by type" or sort by something else that leaves us no choice but to retrieve that information for all items).

However, if I understand your last message correctly, you say that it takes 5 seconds until you actually see the folder contents in the view, right? I'm not sure how much we can do about that in Dolphin itself, but it would be interesting to know how many items are inside that folder and what the files are sorted by. Thanks.

That's very interesting, and sounds like it might be the fix for all big loading times I only run the latest KDE release of my distro so I'll only see the change this autumn for openSUSE. Will it only improve the issue in Dolphin, or also in KDE's file saving dialog (eg: When saving an image from Firefox)?

It does sound like it should improve the loading issue greatly. In my case the slowest folder has about 50.000 images (mostly jpg and png) and I always have Preview enabled in it. At this moment it appears to take a positively surprising 4 seconds to open, on KDE 4.10.3 with "natural sorting of items" turned off.

As for what I'd hope the improvement to be, I know it can't be perfect. But the slowdown caught my attention when I moved from Windows 7 to Linux. The folder was opened instantly in Windows Explorer (at least so fast I couldn't notice) with the same thousands of images, sorting by "date modified", and previews being enabled. I hoped something could be done for KDE to work as fast. It was a noticeable difference (approximately 0.5 seconds [Windows Explorer] to 8 seconds [KDE / Dolphin]).

I only have one concern about the change: When you scroll through items which aren't in the view yet (and therefore are loaded gradually), will Dolphin or other browsers lag? I don't mind the items being loaded slowly of course, but it would be annoying if the program would stop responding every few milliseconds and the interface would block out in the process. That's actually my main issue with the current way... I don't mind waiting 4 - 8 seconds to see mime types and previews, but do mind that Dolphin stops working in the process.

Thanks for looking into it, awesome work! Another reason to wait eagerly for KDE 4.11

To answer your "file dialog" question: no, my patch only affects Dolphin.

To prevent any misunderstandings: The time required for the initial loading of the folder will most likely not change in KDE 4.11 (unless there are some improvements in kdelibs). My patch only prevents high CPU and disk usage which is due to loading icons and mime types after all files have been added to the view.

freininghaus wrote:To answer your "file dialog" question: no, my patch only affects Dolphin.

To prevent any misunderstandings: The time required for the initial loading of the folder will most likely not change in KDE 4.11 (unless there are some improvements in kdelibs). My patch only prevents high CPU and disk usage which is due to loading icons and mime types after all files have been added to the view.

Ahh, ok. Then sadly it won't solve my problem at all most likely. For me it takes several seconds until the files are shown at all (sometimes not even the directory is visibly entered once I click it). When all files are loaded it's almost instant until the mime types and icons / previews are detected, so the bottleneck isn't there.

So I'm still waiting for a knight in shining armor to fix the code in that case kdelibs is a good pointer if that's where the problem is known to lie, and maybe someone who knows the code can take a look it.

Quick question: Which view mode do you use? If it is not Details View, could you check if it becomes faster when you switch to Details View?

I have always used Details View for my "Open directories with many files" tests, but I noticed the other day that Dolphin's layouting code (not written by myself) can become a bottleneck in Icons View because it calculates for every file how many lines are required to show the file name. In Compact View, it is slower as well because it calculates the maximum width for all file names in a column to find out where to draw the next column.

freininghaus wrote:Quick question: Which view mode do you use? If it is not Details View, could you check if it becomes faster when you switch to Details View?

I have always used Details View for my "Open directories with many files" tests, but I noticed the other day that Dolphin's layouting code (not written by myself) can become a bottleneck in Icons View because it calculates for every file how many lines are required to show the file name. In Compact View, it is slower as well because it calculates the maximum width for all file names in a column to find out where to draw the next column.

I use 'icon view' in Dolphin and 'detail view' in the file saving dialog of applications (I'd dislike any other setup). Both are slow last time I checked however.

I hope it doesn't bother anyone that I'm reopening such an old thread. I figured this needs to be discussed more, as the problem seems to have only gotten worse as time went on. I'd say that for me, it's becoming the biggest annoyance with using KDE right now.

I'm running Framework 5 with Dolphin at version 16.04.3. Opening a directory containing 86.000 files takes nearly 40 seconds! It doesn't matter whether Natural Sorting is enabled or not, and after some update a few months ago it actually feels even slower than previous. As usual, the Sorting... step is the time during which Dolphin becomes frozen. To be sure this isn't some general Kernel or ext4 limitation, I ran "ls ./" in the same directory... it took only one second to list every file!

Please developers: Do something about those huge loading times! I understand that big directories take time to load, but more than half a minute? Back when I used Windows, Windows Explorer only took a second itself to open such directories... so something must be wrong somewhere.