Why is there something "wrong"? It is unexpected for you. But this just comes down to two different problems, solved by different algorithms. Depending on the size of the problem, and any specifics, one algorithm may have an easier solution, and thus take less time. In fact, we don't even know if you used good methods to determine the time for each solve. For example, toc and toc are generally a bad way to compute the time required for code. And we certainly do not know what size problem is this, how many variables, how many constraints, are there equality or inequality constraints or both, etc.