Per my experience most applications that mostly serve documents from databases should be able to take on at least 10k requests per second on a single node. this is 600k requests per minute on one node, compared to their 1M per 1000 nodes.
This is what I am typically getting from a simple setup with Java, WebFlux and MongoDB with a little bit of experience on what stupid things not to do but without spending much time fine tuning anything.
I think bragging about performance improvements when your design and architecture is already completely broken is at the very least embarrassing.
> poor hindsight from original developer (co-founder)
Well, you have a choice of technologies to write your application in, why chose one that sucks so much when there are so many others that suck less?
It is not poor choice, it is lack of competency.
You are co-founder and want your product to succeed? Don't do stupid shit like choosing stack that already makes reaching your goal very hard.