Did you run a memory test? Some hardware coupled with the correct memory can do a interleaving thing. Interleaved memory effectively increases CPU access to memory Allowing CPU to run faster.
I have needed to go back to the memory originally installed. boot it up. then add one module of the new (crucial) RAM. boot it up. then shut it down add second module.
and what you have might work.
I do not know how to detect whether interleaving is working and I do not know whether the X230 allows interleaving.
I am pretty sure the reason people used to say, a decade ago Apple supplied memory always runs faster i8s because their own supplied memory had interleaving.