When I select a thumbnail in the Browser there is a significant freeze of between around 1 and 10-ish seconds before I can select another thumbnail. It happens on thumbs for very large images but only for certain formats. Thumbs from tiffs don't (ever) exhibit this freeze (either uncompressed or LZW compressed), same with bmps and jpegs, but the freeze is a couple of seconds for jp2 images (always), around 3 or 4 seconds for WebP (always) and longer for FLIF (always). PNGs cause usually under a second's pause, but still noticeable when clicking between thumbnails.
Specifics: the images are 9600dpi scans of projector slides with pixel dims around 13000 x 9000 px; all 24bit colour. They are compressed losslessly in WebP, PNG or FLIF and done via batch convert by XnViewMP from tifs saved by Corel Photopaint X6 (or my Epson scanner software).
(My PC is a Core i7, 3.40GHz with 12 cores and 32GB of ram, if that helps)
I don't know if this qualifies as a quirk or a bug and maybe should more appropriately be in the bug section, but if whatever is going on during the freeze could be interrupted by selecting other thumbnails, or take place in another thread, that would be fab.
The other issue I have is with the aforementioned batch convert of these files. I have several hundred of these projector film slides to convert from tif to lossless WebP or jp2 and around a hundred-thousand more still to scan and then batch-convert. The advantage of a batch convert is that you can do loads in one go and leave it to it. However a folder of 150/160 images can take around 8 hours to convert and during that time there's no way for me to minimise the application. I can use the Windows-D shortcut to hide all windows but the moment I bring up another application XnView pops back up in the way again. I realise that the batch convert form is probably modal, but a way to minimise the application from that form would be even more fab than the previous fab thing mentioned

Thanks
C