RT significantly slower on Windows than on Linux

Software RawTherapee
21

I will compile on Arch in a minute. Arch shoul use the newest compiler.

22

Just built RT on Garuda. Slower than the Appimage but not nearly as slow as Windows. Jumping to the next raw takes approximately 1.85 sec.
It’s clear that it’s capture sharpening that slows down the process (the c.sh. bar is slower in the bottom left corner).

Going to compile on Windows now.

23

RT compiled on Windows is as fast as compiled on Arch/Garuda

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24

Good job with the investigation, Anna!

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25

I see the devs have already done something:
Set -ffp-contract=off compiler flag for GCC >= 11 (#6384) by Lawrence37 · Pull Request #6583 · Beep6581/RawTherapee · GitHub - I guess that’s what I have tested now? So if I had tested it yesterday it would have been slower…

edit: apparently it’s not merged yet

26

@Lawrence37 's fork seems to be a little faster than dev on Windows, maybe even faster than the Appimage, jumping to the next raw takes 1.5-1.6 secs, maybe sometimes 1.4
Going to compile on Arch…

by the way, there is a mistake in the compiling instructions for Windows, it should be git clone https:// not git clone git://

27

just compiled @Lawrence37 's version, seems to be as fast as the Appimage

28

@Lawrence37 @Thanatomanic I’ve also tested the windows binary from Github, seems to be fixed now.

2 Likes
29

I am a Windows user.
I kept using version 5.8 for a long time, then (when it was clear that version 5.9 was not coming fast) I installed version 5.8-3089-g274c99e9b just to test the new features.
BTW it was april 2022.

The program has a lot of new features but, on my rather old computer, it is much slower and a lot less responsive.
Even simply keeping pressed the mouse over a + or - button near a slider does not change the values in a smooth way but the numbers stop periodically, just as the program needs to rest.
This happens even if I do not use any of the new features, but only the ones that were available in version 5.8 and this looks strange to me.

30

Isn’t this just a fix for a certain GCC version… if it’s windows / linux / macos… there is no platform specific thing in here? Or am I misreading something.

31

the issue was also present if RT was compiled on newer Linux systems with a newer gcc, I think just some new feature in the new gcc was switched off
but I don’t understand the exact technical details
I mean RT was faster on Linux because the Appimage is/was compiled on a really old Linux

32

I’ve found that compiling on Windows yeilds a noticeable improvement over the binary distribution.

Likely due to the optimizations native to my CPU, but but at the very least its a placebo level improvement :slight_smile:

33

The same goes in my experience. I’ve even found that some stuff works smoother and quicker when running on Arch Linux via Virtualbox hosted on macOS than it does by running on macOS directly (don’t ask me how that’s even possible; I just put it down to Linux being better :wink:).

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34

I think what we Windows users are seeing is that the development and pre-release builds of RT that are available on github are being compiled with “generic” features that will/should run on nearly any version of Intel processor. But a generic version doesn’t enable the optimizations available in more recent versions of the processors (Skylake, Haswell, Alderlake, etc.) so the result is a much slower and jerkier performance.