RT is running slow on my new iMac

Ok, as I’m not on Mac I’m out of ideas now. Maybe @HIRAM can help?

It isn’t in ~/Library/Application Support/RawTherapee/config/?

No. In /Library/Application Support/ there is no “RawTherapee”-folder

Your user’s Library, not the system Library. /Volumes/Users/YourName/Library is the path


Have you had luck with the latest dev build:

I tested it now. I can’t tell any difference wrt. my problem. I did, however, discover that one needs to install the program by dragging it to the “Application” folder (having no experience with Macs I didn’t know this). It might be my imagination, but it feels a bit smoother after, though still not as smooth as with my old system.


After some more testing, I have concluded that there is a clear difference in the level of smoothness when I move sliders at full screen and fit the zoom, and when I zoom out as much as possible. It is still clearly sluggish when it is zoomed out but less so than at maximized view.

Make sure you’ve read all three.

Thanks. Interesting reading, though it did not solve my problem.

I upgraded the Mac to a i7 with 16GB RAM and a faster HD. That did not help either. Still, the sliders still seems sluggish, the processing window updates less smoothly than it did for the old linux-machine, and even stuff like the indication/highlighting of buttons when I hoover the mouse over them lags just enough to be irritating. Are there really no-one else who have had similar problems?

We may have experienced similar things, but perhaps haven’t yet classified them as problems. Different things about the interface irritate me. I just updated from i3 to i5 with a 20% gain in freq. it’s a 42 Watt iMac and I’ve maxed out the performance and ram. Sluggish is not a term that pops into mind when using rt. One thing I’m wondering about is if the program still acts slow for you after reinstalling the os.

I could try, though I am not sure why we should expect it to help. After all it is brand new. And when I said that I updated the Mac, I really meant that I replaced it with a new one. As such, I have experienced the same problems on two fresh installations two different pieces of hardware.

It would help if you uploaded a screencast (video) so we can see what you mean.


here is a video showing some general sluggishness.https://pixls-discuss.s3.dualstack.us-east-1.amazonaws.com/original/3X/e/c/ecfc842e8d7f203a67020eda916d70d4268fec85.mp4


Sorry, I now updated the post to actually include the video :slight_smile:

Please test again using RT 5.5 from here

Same trouble it seems: https://pixls-discuss.s3.dualstack.us-east-1.amazonaws.com/original/3X/7/3/7366e8e2e49d9c8e286b1db87b7f309758a40012.mp4

Is this an iMac with 4K or 5K display?

I’ve got the following specs:
Screen: Retina 4K, 21.5-inch
Processor: 3,6 GHz Intel Core i7
Memory: 16 GB 2400 MHz DDR4