Great point, r5.metal instances have 96 CPUs and 768 GB of RAM. Lots of "big data problems" can actually be solved with a single big EC2 instance. Cluster computing should always be avoided when a single node will do.
We had something like 24G of RAM, but we have 500GB RAM machines as well (we own the hardware) and the job would have been even more of a breeze there.
