Q: New imac5K i7 preview app super slow raw photos? Lightroom5 super slow? very disappointed

dellwod, you should take Terence and Timothy with you to the Apple Store so they can explain to the Geniuses how Lightroom 4, 5 and 6 are compatible with OSX 10.11.2 despite what seems to be the experience of most users using iMac 5ks and what Adobe has to say.

Good Luck.

welcome.

I suspect that if you did a clean install and tried Preview before migrating anything over you would find Preview opens your images normally. Of course few people want to bother.

While you're there you could show them this screenshot:

No one said Lightroom 4 wouldn't load Timmy.

Actually someone seemed to strongly suggest that on more than one occasion. Let me see ... yes ... that's right ... it was you.

Actually I never said that. I said it was outdated, I said it wasn't compatible. I said there are problems running it on a 5k Retina iMac. I said Adobe also mentions the problems and posted the link. But nowhere did I say it wouldn't load. It would help if people could read.

Here's a screenshot for you…

From Adobe's Lightroom 4.2 page. https://www.adobe.com/support/downloads/detail.jsp?ftpID=5487

I don't see 10.11 mentioned, or 10.10 or 10.9 for that matter.

This crowd sourced website is used quite often in checking application compatibilities; here is what I found when I searched for Lightroom:

Some older versions appear to be compatible (although some have the "works with some problems indicator"); here you can look at the full list of apps:

http://roaringapps.com/apps?platform=osx

well there you have it, proof Adobe is wrong.

"appearances can be deceiving"

You did bring up a point. To me, a compatible application is one that works as it was meant to, not one with some issues.