Scalability question?

Hi there,

There have been some internal debates here about how far we can scale
Kafka. Ideally, we'd be able to make it scale to 90 billion events a day.
I've seen somewhere that linked scaled it up to 40 billion events a day.
Has anyone seen a hard plateau in terms of scalability? Does anyone have
any advice for tweaking configs to achieve ultra-high performance?

Thanks,