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Five benchmark-gated optimizations from a fresh six-way audit (benches/ROUND25.md), each with a BEFORE/AFTER gate that rolls back if AFTER does not beat BEFORE: - M1 EncryptedBlobBackend::decrypt_bytes: replace split_off (a fresh Vec + full ciphertext memcpy on every decrypted chunk, contradicting its own "in place" doc) with in-place detached decrypt + a zero-copy Bytes::slice past the nonce. Peak RAM per read drops from ~2x to ~1x the payload (-262KB/op at 256KiB; scales with blob size). Plaintext byte-identical; tamper/wrong-key tests pass. - M2 delta commit: move-unzip the owned chunk list instead of a third per-occurrence hash clone (-4000 allocs on a 4000-chunk commit). - M3 folder ZIP download: drop the dead Query<HashMap> extractor it never read (byte-identical response; 5->0 allocs/request). - Q1 public-playlist listing: fold the per-playlist COUNT(*) N+1 into one LEFT JOIN ... GROUP BY via a new inherent repo method (101 -> 1 round-trips, 36x wall on a 100-playlist page). - Q2 contact REST listings (paginated/search/by-group): stop over-fetching the multi-KB vcard TEXT the ContactDto discards, via a shared lite row mapper and narrowed SELECTs (6.4x wall on 1000 contacts with 8KiB vcards). The whole-book vCard export and CardDAV sync paths keep the column. Adds bench_round25_micro (counting allocator tracking count+bytes) and bench_round25_queries (live Postgres), both with equivalence gates and a rollback exit(1). Verified: cargo fmt clean, cargo clippy -D warnings clean, cargo test --lib --features bench = 529 passed / 0 failed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01L8gs91AhmazoxMsDcNk3KT