It's called super linear scaling. If you have a fixed size problem, that doesn't communicate much, and is CPU intensive you can run on a single core and be lim

It's called super linear scaling. If you have a fixed size problem, that doesn't communicate much, and is CPU intensive you can run on a single core and be limited by memory bandwidth or latency. But as you use more cores you can fit in L3, L2, and even L1 as you add more cores. It's seen sometime even on multinode jobs. But it's definitely the exception to the rule, but it does happen. It's helped by the fact that each level of cache is approximately 10x faster, so fitting in a cache is a huge win. So running in ram on 1 node might be 20x slower than running in cache on 10 nodes.