Summary: Real-time anti-virus scanning of the Opus thumbnails cache can significantly slow down thumbnail generation.
This problem is less likely to occur in Directory Opus 9 because the thumbnail cache is split into more, smaller files than in previous versions.
Although it doesn't happen with all anti-virus products and configurations it is possible for real-time virus scanning to significantly slow down Opus's thumbnail generation. This can happen when the real-time scanning causes delays when Opus is trying to write files into its thumbnail cache.
Here is a quick and easy way to see whether or not this is affecting you:[ul][li] Go to Preferences, Listers, Thumbnails.[/li]
[li] Click the Settings... button to open the thumbnail cache dialog.[/li]
[li] Click Empty to clear the thumbnail cache.[/li]
[li] Open a lister showing a directory with lots of image files (only -- no video or other files) which are all about the same size, such that each file in the directory should take approximately the same time to process.[/li]
[li] The first few thumbnails should generate quickly.[/li]
[li] If your anti-virus scanner is getting in the way then you'll see that things slow down considerably as more and more thumbnails are generated. This is a factor of the size of the thumbnail cache, not the number of thumbnails in the current directory.[/li]
[li] If you don't see the slowdown then you don't have a problem and don't have to do anything to your virus scanner.[/li][/ul]If you now see that your virus scanner is slowing down thumbnail generation then you have the option of fixing the problem by telling the virus scanner to ignore the Opus thumbnail cache directory. (You can find out where the cache is stored by going back to the Settings dialog under Preferences...)
Of course, any changes you make to your anti-virus configuration are done at your own risk. If you don't want to leave a directory on your system potentially exposed to viruses then you'll either have to put up with the slowdown or consult your anti-virus vendor.
Note: Slow thumbnail generation can be caused by other things, not just anti-virus. For example, if you have changed the RAW camera plugin to do full decodes for thumbnails (not recommended!) then it will take a very long time to generate thumbs for raw images. Buggy video codecs that go wrong can also slow down thumbnail generation, and so on.