[JoachimSchipper]

> Compute-optimized (C) instances can substitute for a general-purpose (M) instances of half the size

They do have the same amount of memory (and twice the CPU). But if you run a workload that automatically scales to the number of available cores, starting twice the number of processes / threads might well run you out of memory.

The article is interesting, but blindly running your code on unexpected instance types may be more "exciting" than the author makes it sound.

[ericpauley]

Author here. If you design the workload you can ignore the extra instances. You can actually hide these cpu cores from instances within the AWS api (see setting instance vCPU) so it is truly transparent.