fsenore
December 28, 2025, 4:01pm
1
I am using RawTherapee 5.12 in a Windows 11 Pro computer, Intel Core I7-14700, 32 GB RAM. It’s an HP Z1 G9. I downloaded RT from the official web site.
Everything in RT is fast, but Dynamic Range Compression is unusable: if I turn it on with a 20 megapixel image the result shows up after 9 seconds. It used to be almost in real time in a much older computer.
Do you have ant suggestion to make that feature usable?
Thanks in advance.
Fulvio Senore
Phil_Smith
December 29, 2025, 8:18am
2
Are you able to attach the RAW file to allow others have a go on their system please? If it’s slow on our systems too it points to the image rather than your system.
marter
December 29, 2025, 11:38am
3
i think this issue was reported here:
offen 02:56AM - 19 Dec 25 UTC
scope: performance
**Short description**
Whenever I try to use dynamic range compression -- it's t… erribly slow.
Changing any slider requires me to wait dozens of seconds before I see the result and can change anything again. UNLESS zoom is 20%.
So, I noticed that when zoom is set to 20% CPU core utilization is even, and it uses all of the cores. Which is 16 (or 32 with HT) in my case. On other zoom levels, e.g. 14% or 50% or 100% or 25% only about 4-5 CPU cores are utilized.
My raw files are large, Sony A7RV raw file with lossless compression.
**Steps to reproduce**
1. Open SONY A7RV losslessly compressed raw file
2. Load neutral profile
3. Enable dynamic range compression
4. Open task manager, performance TAB
5. Make sure you have more than 4 cores displayed there (32 preferred)
6. Set zoom to 14%, 25%, 50%, 100% and observe core utilization while dragging `Amount` slider of DRC rapidly.
7. Observe uneven core utilization in task manager
<img width="2095" height="669" alt="Image" src="https://github.com/user-attachments/assets/fb81b45e-cd25-4aa9-a52a-7bfe6871526e" />
9. Set zoom level to 20% and and observe core utilization while dragging `Amount` slider of DRC rapidly.
10. Observe all cores being utilized and almost immediate changes in rawtherapee.
<img width="2106" height="632" alt="Image" src="https://github.com/user-attachments/assets/5d2fd2ae-9234-4ebc-a33a-c707a4baeb94" />
**Expected behavior**
If it's possible to evenly spread work between all cores (which is proven at 20% zoom), it should be possible to do the same no matter the zoom level.
**Additional information**
- RawTherapee 5.12
- OS Name: Microsoft Windows 10 Pro
- OS Version: 10.0.19045 N/A Build 19045
- System Model: MS-7C84
fsenore
December 31, 2025, 11:10am
4
Thank you for finding the Github issue. It is probably the same thing: showing the image at 20% is much faster. I added a comment.
Anyway, it’s curious that a feature that worked in previous versions fails now in such a spectacular way.
I wonder if there’s a problem with some hardware or simply nobody uses this feature.
1 Like
marter
December 31, 2025, 1:14pm
5
I am using this feature, but never experienced a delay as you do or as described in github.