I am using XnView Pocket 151 on a HTC Pro (VGA resolution, 525 MHZ processor, running Win Mobile 6.1), the micro SD card in my device has class 6, so I suppose the whole stuff should be pretty fast. Browsing and displaying 2-3 Mpix JPEGs is nearly instant, the slideshow functionality only with JPEGs is also very responsive.
But the problem comes with Rraw/ORF file. When I go to my raw files shot with my Olympus E-510 (ORF file format), the thumbnail list appears quite quickly, but when I doubleclick a thumbnail to display the photo, it takes 30-40 seconds to display anything, and the device is frozen meanwhile.
Based on this behaviour I think that in full resolution display mode XNview-pocket tries to process every time the raw information of the picture, while for the thumbnail view it is quite obvious that only the embedded jpeg (preview) photo is used..
Would it be possible to speed up this by displaying in full resolution mode only the Jpeg that is embedded in the raw(ORF) file at its full size? I mean - have a setting in the configuration that would allow to switch between the two modes: process the full raw data or display the embedded jpeg only.
FYI, my Olympus E510 generates a quite usable 2mpix thumbnail photo that I usually extract for preview/preprocess purposes using the "Instant JPEG from RAW" (IJFR) utility. This way I only shoot in raw mode, but I can display/provide quite quickly some JPEG pictures, too. This feature helps me save space on my storage card in the camera, because I don't need to shoot in RAW+JPEG mode
If you think this functionality - or any other way to speed up raw file display - would worth a try, I could test this functinality with raw files from the folowing cameras: Olympus E-510 (my own camera) and Canon EOS 450D or Nikon D90 (owned by some friends), or other files from other cameras downloaded from various photographic sites.