Batch processing much slower in 2.10 compared to 2.8
GIMP version: 2.10.2
Operating System: Windows OS
Package: Installer from gimp.org
Description of the bug
I developed a batch processing script using scheme and running on 2.10.2 compared to 2.8.22 it is much slower. I ran a sample test on about 1000 images and in 2.10.2 it took 14 minutes 50 seconds to finish. In 2.8.22 it took 5 minutes 56 seconds. For both versions I had use 8 threads in my preferences, and in 2.10.2 I tried with and without hardware acceleration, which on my set up didn't seem to improve anything. This is a small sample compared to the full set of data that this batch process is typically run against. Typically it will be run against millions of images, so with 2.10.2 a process that would take ~300hrs on 2.8.22 would take about ~750 hours instead to process.
Is the bug reproducible? Always
Attached is the scheme script I am using batch-optimize-images.scm An example of running the script from PowerShell is shown below
$gimpConsole = "C:\Program Files\GIMP 2\bin\gimp-console-2.8.exe"
$gimpOutput = & $gimpConsole -i -b "(batch-optimize-images `"$gimpPattern`" $gain $standardDeviations)" -b "(gimp-quit 0)" 2>&1;
Where $gimpPattern is a GIMP pattern string for processing multiple images in a folder and $gain determines the percent amount of boost (default for my program is 0.3) and $standardDeviations defines where the histogram curve will be boosted (default for my program is 1.5)
Expected result: To take about as long as it took with 2.8.22
Actual result: It is taking about 2.5 times longer