Default to performance-aware coding for hot paths (proxy routing, request parsing, metrics/serialization, and request body handling): - **Avoid unnecessary periodic work**: only schedule timers or run refresh logic when the correctness mode requires it. - **Do not add extra O(n) work in hot paths**: avoid length/count scans like `tb_nkeys()` on request-critical structures; prefer constant-time checks (e.g., `next()`-based) or use existing router-provided capture counts. - **Reuse per-module/per-conf objects**: never allocate metatables/functions/large helper tables inside request-handling functions when the structure is reusable. - **Minimize nginx/Kong accessor overhead**: prefer the cheaper single-value accessors (`ngx.ctx`, `ngx.var.http_content_type`, `ngx.header[name]`) over higher-level helpers when the value is already available. - **Eliminate redundant per-request work**: ensure request body reads happen only once per request lifecycle. - **Guard expensive debug logging**: don’t build JSON/strings for debug logs unless debug logging is enabled. - **Measure before simplifying**: if you propose a code simplification in a performance-sensitive utility, require a microbenchmark/profile result—simpler code can be slower. Example (constant-time capture check + localizing `next`): ```lua local next_ = next -- captures = { [0]=full_path, [1]=cap1, ... } local function has_uri_captured(captures) if not captures then return nil end -- constant-time check for any key other than [0] if captures[1] then return captures end return next_(captures, 0) and captures or nil end ``` Example (reuse metatable outside the hot function): ```lua local payload_mt = { __newindex = function(t, k, v) -- set dot-path values end, } local function build_payload(template_payload) return setmetatable(template_payload, payload_mt) end ``` If you’re unsure whether a change is beneficial, treat it as a performance work item: profile/flamegraph or microbenchmark it under realistic inputs before merging.