Performance: Optimization opportunities (35-45% throughput improvement)

[dshkol]

Summary

Meta-issue tracking 13 performance optimization opportunities identified in code audit.

Performance Items

ID	Location	Issue	Expected Gain
P1	cansim.R:365-379	fold_in_metadata repeated left_joins	50-70%
P2	cansim_metadata.R:98-111	parse_metadata nested loops	60-80%
P3	cansim_parquet.R:675-715	cached_tables repeated reads	65-85%
P4	cansim_metadata.R:127-145	hierarchy O(n) cycle detection	40-60%
P5	cansim.R:156-162	gsub loop in factor conversion	30-50%
P6	cansim_parquet.R:254-263	field cache read miss	70-90%
P7	cansim_parquet.R:219-232	csv2sqlite transform copies	25-40%
P8	cansim_vectors.R:20-24	lapply to vapply	30-45%
P9	Multiple files	French string constants	20-35%
P10	cansim.R:64	unnecessary as_tibble	5-15%
P11	cansim_metadata.R:123-124	hash lookup for parents	80-95%
P12	cansim_vectors.R:244-251	coordinate metadata loop	35-50%
P13	cansim.R:885,889,898	lapply unlist chains	20-30%

Proposed Implementation Plan

• PR 4: Hot Paths (P1, P2, P5, P13)
• PR 5: Caching & I/O (P3, P6, P7, P10)
• PR 6: Lookups & Vectorization (P4, P8, P9, P11, P12)

All performance PRs will include microbenchmark results.

---

From code audit - 35-45% overall throughput improvement potential