OpenCV 4.4.0 is slower than OpenCV 3.4.1

I made c++ algorithm for making panorama images with OpenCV.
It takes about five times more time to run the algorithm at OpenCV 4.4.0 than when I ran the algorithm at OpenCV 3.4.1.
I built OpenCV with CMake 3.14 + Visual Studio 2019. Is there anything I can refer to for faster operation?

How was OpenCV 4.4 built?
Normally slowdowns can occur if:

  • multithreading is not enabled (OpenCV built without TBB or OpenMP support)
  • GPU not enabled (CUDA or OpenCL for certain algorithms)

The 5x slowdown seems like a single-threaded run against a multi-threaded run on a 8 core system (as not everything can be parallelized to get the 8x speedup). Check in the System monitor how many CPU cores are running in each case.
I don’t know the panorama stiching algorithm, but I doubt it was replaced betveen V3.4 and v4.4 with a significantly slover version.

Try to rebuild OpenCV 4.4 with TBB support. Otherwise you should be fine with OpenCV 3.4 too.

please present everything you do. we can’t help if you won’t show what’s going on. that includes source code.