The Problem We Were Actually Solving At 12 k concurrent users, the Golang-based treasure-hunt engine began allocating 2 GB of heap in <250 ms. A 512-byte event message ballooned into 4 MB after being processed through a nested map[string]interface{} structure. Allocations triggered three full GC cycles before the response escaped the handler, violating our SLA of <50 ms p99. Running go tool pprof revealed 68 % of CPU time inside yaml.Unmarshal, but we could not patch the allocator without risking a rewrite of the entire event pipeline. What We Tried First (And Why It Failed) We swapped syaml.v3 for go-yaml.v3, expecting a 2× speed-up. Metrics showed p99 down to 187 ms, still unacceptable. Digging into the heap profile, v3 still materialized the entire document before streaming could begin—our real cost was the intermediate in-memory tree. We next rewrote the schema layer in protobuf and generated Go with gogoproto.…