I'm on one of the most recent revisions of opencv (compiled from source): 1ae27eb
(I compiled it with opencv_contrib if that matters).

Once I moved from official release to the one I mentioned earlier, matrix decomposition became really slow (10^3 slower!).

solve(X, Y, res, CV_SVD);

Please find X and Y matrices in attachment, hope it helps to reproduce the issue.
data.txt