solve (cvSolve) became twice slower after updating to OpenCV 2.4.6

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I have been using OpenCV 2.2.0 and I haven't had any problems with performance. After updating the library to the latest version (2.4.6) cvSolve function started taking about twice the time it used to take before. I haven't changed the algorithm anyhow, I have only updated the library. I am using pre-built libraries on Windows with VS2010.

What could be the reason of performance drop?