Benchmarks

The bench/ directory holds a reproducible speed comparison against Presidio's Python analyzer. Both engines read the same generated corpus (186 documents across a {100 B, 1 KB, 10 KB, 1 MB} × {no PII, sparse, dense} matrix, every seeded value passing its real checksum) and emit the same JSON schema, so results merge into one table.

Representative single-threaded run, with Presidio configured to use its slim tokenization-only NLP engine, the closest match to Alcatraz's pattern-only core (its default spaCy-NER pipeline is slower still):

Corpus group	Alcatraz ms/doc	Presidio ms/doc	Speedup
100 B, no PII	0.09	8.5	~100x
1 KB, no PII	0.80	15.2	~19x
10 KB, no PII	8.0	84.3	~11x
10 KB, dense	8.7	116.1	~13x
1 MB, no PII	840	7,999	~10x
1 MB, dense	1,521	159,237	~105x

A parity check also diffs the detections of both engines on the same corpus. On the shared entity types (credit cards, IBANs, SSNs, IPs, bank numbers) the two agree span for span; they diverge where recognizer sets differ (e.g. Presidio ships no Brazilian recognizers).

Numbers vary by machine; reproduce them with two commands per engine. See bench/README.md for setup and methodology.