RT is running slow on my new iMac

(Børge Rokseth) #1

Hi, I just purchased a new imac 21.5" One of the standard ones with 4k, 8gb, i5 3.0ghz. I went for the cheap HD. I thought this would be plenty good as I prevoiusly had been running RT from an 2012 laptop with a 4gb, i5 processor running Ubuntu.

Now, with the new imac I find that when i use the sliders to adjust just e.g. exposure, contrast, temp, or anything, or manually adjust tone curves, things are lagging and jerking so much that it is hard to operate them with any precission. I find the same problem on all distributions I tried (all 5.x)

What is wrong? I am aware that the machine I bought is not the most powerful machine on the market, but still, its a lot more powerful than the previous machine I had, which ran RT just fine. Is Ubuntu that much better than OS X, is RT not optimized for OSX, or did I just get a monday edition?

And what should I do? Should I return the imac/upgrade it? If so, is RAM, a faster processor or faster HD the way to go?

(Ingo Weyrich) #2

Did your previous machine also have a 4k display?

(Børge Rokseth) #3

No, it did not. It had a HD display. Do you think thats it? I thought there where an independent graphic card to handle the display.

(Ingo Weyrich) #4

The processing time for the preview area in RT scales roughly linear with the number of pixels of the preview area => larger preview area needs more processing time.

Maybe try (just to verify my statement) to reduce the size of the rt window.

(Børge Rokseth) #5

I tried. I can’t say I noticed much difference between a very small window and full screen.

After dragging a bit up and down on the tone curves just to test, i notice that it may work fine for a few seconds (dragging constantly up and down) then it may suddenly start lagging and jerking for a few momenents (as though the machine suddenly found something better to do)

Are there other processes than updating the display which may be hard for the machine to cope with in such a situation?

(Ingo Weyrich) #6

Can you post the values of the following keys in your options file, please?


To find the options file:

(Børge Rokseth) #7

I am sorry, but cannot find the file. I can’t even find the RawTherapee-folder in the Application Support folder.

(Ingo Weyrich) #8

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

(Mica) #9

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

(Børge Rokseth) #10

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

(Mica) #11

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

(Børge Rokseth) #12



Have you had luck with the latest dev build:

(Børge Rokseth) #14

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.

(Børge Rokseth) #15


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.

(Morgan Hardwood) #16

Make sure you’ve read all three.