And it is not like you can buy a computer significantly faster that what I have, short of dual-processor workstations in $10K range. Now I have to press that button all the time, because previews just don't show anything close to the final results at all. I did not have a problem before, as previews were realistic. I wonder how much Lightroom is faster than this. But horribly slow to add upgrades for new cameras. The fastest RAW converter that I've met is Corel AfterShot Pro, versions for Win/Mac/Linux and has a 30 day trial to see if it works for you.
Jpeg is simple adjusts, RAW is about the 4 pixel RGGB interpolation into single RGB pixels, plus the adjusts. Their JPEG editor works much faster for some reason. Yes, it is slow, but thorough ! You get what you pay for and it is very good for a freebie, especially as it can also handle all brand camera jpegs. To the point of them having a button to actually preview (and their 'fast' preview is really just not really previewing anything even at half-screen resolution of the preview window). Is it just me, or Olympus Viewer 3 really processes RAWs so much slower (compared to Viewer 2)? I mean, it takes like 20 seconds (more if I touch certain settings) to process a file on a Core i7 3.4GHz, plenty of memory, SSD.