RawTherapee 5.9 - problems and crashing

Hi all! I searched and couldn’t find any particular hints. I’m a long-term RawTherapee user (nearing 10 years!). This year I have been using 5.8, and this week I decided to download 5.9. It’s not going well, and I’m looking for obvious hints/tips before I go toward filing a bug report.

  • I downloaded the stable release from the public front page.
  • I’m running Windows 11 (fully updated). Machine is a MS Surface Pro 8 (Intel I7-1185, 32GB ram, Iris Xe graphics).
  • I installed 5.9 alongside 5.8. My settings imported/shared(?) seamlessly. (<-- I wonder if this is part of the problem)


  • Upon open, 5.9 is immediately much slower to open and respond than 5.8 was.
  • I like to open 5-8 photos at once and go back and forth. On 5.8, I was able to open about 10 before it said I couldn’t open more. On 5.9, it only let’s me open 3.
  • seemingly randomly, as I open and close photos 5.9 hard crashes.

Thoughts? Obvious things I’m missing? thanks!

Hello, I guess that’s a Windows problem. On a Linux machine with only 8GB of RAM, I can open 18 jpgs/nefs in RT 5.9 before the memory indicator starts blinking red…

5.9 introduced Local Adjustments which is a very big addition. If you create a spot, add all the available tools, set the interfaces to Advanced, and expand everything (or try too), you will see that there are literally hundreds if not thousands of sliders, spinners, buttons, and text labels. All of these “widgets” need to be created when you open RawTherapee. That may explain your first problem.

Those widgets also consume “GDI handles”. The Windows limit of GDI handles means you can only open so many editor tabs before running out. The number of GDI handles required by Local Adjustments means you will run out much sooner than with 5.8. This may explain your second problem.

The third issue is hard to diagnose because there isn’t enough information to go on. If you have the time, you can try one of the debug builds (instructions are on the RawPedia page for reporting bugs) and capture the crash details.

In theory, it is possible to optimize the startup speed and use of GDI handles, but of course there is a development cost. That said, the current development version might already have better performance due to some changes introduced along with the Favorites tab improvements, but I have not compared the speed or maximum number of editor tabs.

For maybe only the third time ever in the last 5 years, RawTherapee (5.9, in this case) just crashed on me today. I was using Local Adjustments and was probably taxing its resources pretty hard.

Thanks Lawrence. Your explanations make a lot of sense, and can explain some of the behavior. It also helps explain why cross-platform SW is hard… I was a primarily-linux user for about 15 years, and so I’ve been curious to try RawTherapee back on linux since I understand the performance is better… I just don’t have the time to fiddle any more, etc. Sigh.

I’ll take your advice to try the debug builds, and maybe move toward a crash report. I stuck with 5.8 for now to get my current photography project done, though.

Rick - is this on linux or windows? RawTherapee used to crash regularly for me but 5.8 was rock solid on Windows.


5.9 on Windows. I don’t expect it to be a problem moving forward, though.