It's worth pointing out that the L1 cache and its associated logic is the only* way a core talks to the outside world, including all I/O ever. With that in mind

It's worth pointing out that the L1 cache and its associated logic is the only* way a core talks to the outside world, including all I/O ever. With that in mind it is easy to understand why it is so crucial to performance. * there might be some minor exceptions