lstahlman
> Mirrored from upstream: https://github.com/opencv/opencv/issues/28253 > Original author: @soemay · created 2025-12-19T18:52:24Z > Upstream labels: `bug`, `optimization`, `category: imgproc` > Selection: mirrored by mirror-issues.py --- ### System Information Tested with OpenCV 4.11, 4.12 (official windows packages) Windows 11 (64-Bit) Compiler: MSVC Version 19.44.35222 (Visual Studio 2022) Tested CPUs: Intel Xeon W-3335, AMD Ryzen 5 3600 (no AVX512, does not show regression) ### Detailed description Observed Timing: **Intel Xeon W-3335** OpenCV 4.11: ~32 ms average OpenCV 4.12: ~94 ms average **AMD Ryzen 5 3600** OpenCV 4.11: ~32 ms average OpenCV 4.12: ~30 ms average (reason no AVX512?) I assume the last changes from https://github.com/opencv/opencv/pull/27299 caused this behaviour. Because if i revert these changes and compile OpenCV 4.12 myself I get the same performance as in OpenCV 4.11. ### Steps to reproduce ``` cpp #include <opencv2/opencv.hpp> #include <iostream> #include <opencv2/imgproc.hpp> int main() { cv::Mat randomMat(5000, 5000, CV_8UC1); cv::randu(randomMat, 0, 256); const int runs = 100; cv::TickMeter tm; tm.start(); for (int i = 0; i < runs; ++i) { cv::medianBlur(randomMat, randomMat, 5); } tm.stop(); std::cout << "Elapsed time avg: " << tm.getTimeMilli() / runs << " ms" << std::endl; return 0; } ``` ### Issue submission checklist - [x] I report the issue, it's not a question - [x] I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution - [x] I updated to the latest OpenCV version and the issue is still there - [x] There is reproducer code and related data files (videos, images, onnx, etc)