Massive performance issue appeared in the last 3 weeks using View

[bitwash]

I've been using XNview classic for quite a while to browse folders with lots of images (sometimes five thousand or more) and it used to be incredibly fast. I'd double click an image in explorer, View would open, and I'd mouse wheel up or down to step forward or back through the images.

But something happened in the last three weeks or so. Opening View still happens instantly, but trying to step back and forth through the images causes XN to freeze completely (task manager reports it Not Responding) and 2 of my CPU cores to jump to 100% utilization. This lasts for anywhere from 10 to 50 seconds depending on the number of files in the folder. After XN finishes whatever it's doing, I can again step back and forth through the folder image by image with no issue. I was using version 2.51.1, so I tried updating to 2.51.5 but the issue is unchanged.

This doesn't seem like a system resource issue (I'm using it on a 13700k, 32GB of ram, and a Gen 3 NVMe SSD, Windows 10), and my best guess is XN View is reading something from all the files in the directory (date, meta data, etc.) before displaying the next image. As an experiment I tried XN Classic on a less powerful machine (with a Ryzen 5600G CPU) and see no performance issues at all when viewing a folder with over four thousand images in it.

I've been toggling some of the options in Options>View on and off but I've seen no change so far. Anyone have an idea what's happening?

EDIT: I should add I also have XnView MP installed and it runs just as well as Classic used to. No issues when using View to browse folders with lots of images, super snappy.

[xnview]

do you have a lot of files in the folder of image shown?

[bitwash]

do you have a lot of files in the folder of image shown?

In most cases the folders have nothing but images in them (typically JPG or PNG). But some may have a few non-image files.

[xnview]

could you try with a simple folder (only 4/5 image files)?

[bitwash]

could you try with a simple folder (only 4/5 image files)?

I'm seeing no issue with 4 or 5 images in a folder. There is no noticeable pausing until about 40-50 images. The problem seems to scale with the number of images. Every 50 to 100 images seems to increase the wait by maybe another second.

I'm just not sure why I'm seeing this problem now. I've never seen this issue before. I'm thinking of doing a complete uninstall and re-install to see what happens.

[bitwash]

Getting close to an answer now. I uninstalled and then re-installed XnView Classic Minimal/Small (I picked Minimal just to cut down on the number of additional variables). No change, still very slow.

I then uninstalled using Revo Uninstaller to look at the files left behind by the XnView uninstaller. It looks like the "AppData\Roaming\XnView" folder doesn't get removed. I backed up and deleted that folder, re-installed XN and now it's back to full speed.

Looks like the "xnview.ini" from my original install is causing the issue. By swapping between the old ini from my previous install and the new ini from the fresh install I can make the issue appear and disappear just by changing out the ini.

I'm currently going through both ini's to see if I can find which line is responsible.

[bitwash]

Found it.

Line 9 of the ini (under the Browser tag) is called ArrangeBy=

My old ini (from the slow XN install) was this:
ArrangeBy=4

The fresh install ini is this:
ArrangeBy=7

If I manually set my old ini to ArrangeBy=7 the problem goes away.

Pierre, can you tell me what the ArrangeBy= setting controls?

[xnview]

ArrangeBy is the 'sort by', so you has 'Sort by Type'

[bitwash]

Yep, that's totally what it was. Oddly enough setting Sort By to Extension doesn't seem to have any performance hit and does what I need. I'll use that instead of sorting by Type. Thanks!