DT 5.5 dev build running slow on Windows 11

Software darktable
1

I’ve been testing nightly builds and found there’s significant lag in response when I adjust modules. I noticed this about the point when the AI features were added, but this still happens with AI processing turned off. I have Open CL enabled, just as I had before with 5.4

I’m currently on build 5.5 1499 and just wanted to see if others have experienced this before or if there’s some other insight before I submit a report on GitHub.

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2

A possible fix just got merged…

commit 7199f47a2aa78a98c196a3c867a9f0eb3b5321e8
Author: Hanno Schwalm hanno@schwalm-bremen.de
Date: Sun May 31 16:29:16 2026 +0200

Fix CPU HQ darkroom performance regression

In darkroom HQ processing mode we certainly want it's input data to be made an important cacheline
as that would be the best starting point in the pipe.

As this is about piece input for CPU and GPU pipes the iop flag was renamed to emphasize this.
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3

That’s great. I’ll test it out as soon as I can. Thank you @hannoschwalm !

4

I have just installed 5.5 +1523 weekly build and was impressed how quickly it loads at start up. No sluggish behaviour observed yet from me.

5

I was having problems with sluggish lag time during edits. A single slider adjustment to Tone Equalizer would take 10 seconds to process. Hopefully this update fixes the problem

6

I can only agree — the new version 5.5.0.1523 runs significantly faster on my Mac M1.

7

I can also confirm that DT 5.5.0-1523 runs faster on Windows. Thanks!

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OpenCL or CPU? Darkroom HQ mode on or off?

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I’m running with OpenCL activated and HQ mode off. Your fix seems to have improved the lag significantly, but I’m still seeing a delay of about four seconds between clicks on exposure, color calibration and tone equalizer. But I want to test against the the current release to see if it’s any different.

10

I ran a side by side with the same photo and identical settings on DT 5.4.1 and 5.5-1523. I cycled color calibration gamma back and forth to see how long each took to process. Both programs had Open CL activated and HQ processing off.

DT 5.4 cycled 19 times over 30 seconds on an average of 1.5 secs
DT 5.5-1523 cycled 6 times over 30 seconds on average of 5 seconds.

So it does seem there is some lag between the two. I’ve attached screenshot videos

This is DT 5.5-1523:

And this is DT 5.4.1:

I don’t know if this matters, but both versions take about the same amount of time to process if they both have HQ processing activated.

11

Please post logs using -d pipe from both versions of dt.

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12

Do you want me to continue here or as an issue on GitHub?

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I ideally GitHub.

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