No, I'm talking about handling requests. In this particular case, requests (32 to 64 bytes) were flowing through several services (on the same computer). I replaced the processing chain with a single application to remove the overhead of serialization between processes. Requests were filtered early in the pipeline, which made a ~55% reduction in the work needed.
Requests were then batched into succinct data structures and processed via SIMD. Output used to be JSON, but I instead wrote a custom memory allocator and just memcpy the entire blob on to the wire.
Before: No pre-filtering, off-the-shelf databases (PSQL), queue system for I/O, named pipes and TCP/IP for local data transfer. Lots of concurrency issues, thread starvation and I/O bound work.
After: Agnessive pre-filtering, succinct data structures for cache coherence, no serialization overhead, SIMD processing. Can saturate a 32 core CPU with almost no overhead.
[1] https://www.techempower.com/benchmarks/#section=data-r13&hw=...