A performance deep-dive comparing PostgreSQL 17 and 18 using real production query patterns on identical Azure environments. Five key planner and executor improvements are benchmarked: (1) OR-to-ANY transformation that replaces multiple bitmap index scans with a single index-only scan (~43% faster); (2) B-tree skip scan enabling composite index use without the leading column (~1,741x faster on low-cardinality leading columns); (3) self-join elimination that detects redundant joins on primary/unique keys (~5x faster); (4) GROUP BY pruning extended to unique NOT NULL indexes, not just primary keys (~260x faster); and (5) cleaner EXCEPT/INTERSECT hash set execution (~1.5x faster). All improvements are automatic — no query or schema changes required, just upgrading to PG 18.