Cutting Threads’ send latency in half

What this post added

This post details optimizations made to the server media ingestion 'configure' endpoint for Instagram Threads to reduce send latency. The primary improvement involved identifying that the endpoint spent significant time waiting on I/O due to a write-through cache database. To address this, a routing rule was implemented to force requests to a faster region when a special HTTP header was present, effectively batching cross-region round trips to the backing store and reducing overall endpoint execution time, leading to a 29% reduction in send latency.