[ianleeclark]

I don't know if 5-10% difference in write speed and 75% in read speed is "so close to C implementation." These are both operations that will be happening thousands/millions/+ times per day, so it feels incorrect to say they're close.

These read/write differences will compound to make the rest of the data processing pipeline slower.

[wtetzner]

They already commented on that performance:

> Yes, Pony Kafka is currently slower than the C client. But it is also almost completely untuned as of right now. We expect there is a lot of low hanging fruit on that front that will give us significant gains.

>There is also the secondary concern regarding the thread pools internal to Pony and librdkafka. We've seen first hand how CPU cache invalidation can impact performance so we are very aware of the potential negatives if the Pony and librdkafka threads ever end up fighting with each other over the same CPU resources.

[klibertp]

For the first, proof-of-concept, no-optimizations-applied, version of a low-level library written from scratch in a high-level language to be anywhere near production-ready, presumably optimized C implementation is actually very impressive. I'd expect the new implementation to be an order of magnitude (or more) slower than the C one, initially, and only get better with many rounds of optimizations in the following months.