Payload Size

Size is the axis shorn leads. Every number is from pnpm bench:all on Node v22.23.1, Apple M4 Pro, macOS arm64.

Raw bytes

Codec	Person	Unicode person	Nested event	100 events
shorn	8	31	43	4,135
Avro / avsc	8	31	44	4,249
SchemaPack	9	32	44	4,235
msgpackr shared records	10	33	52	4,993
Protobuf.js reflection	11	34	57	5,684
cbor-x shared records	14	38	62	5,972
@msgpack/msgpack	23	46	115	11,281
msgpackr plain	25	48	121	11,881
cbor-x plain	26	50	122	11,972
JSON	35	58	163	16,148

shorn is smallest or tied on every fixture. Two caveats apply: bare shorn, Avro, and Protobuf payloads require the correct schema outside the payload, and shared-record sizes exclude their record table.

The Unicode row shows where the savings come from. shorn removes field names, tags, and syntax, but it does not shrink string content. Payloads dominated by structure and numbers can be about 75% smaller than JSON. Payloads dominated by free text see smaller gains.

Compressed, 100,000 events

Repetitive data

Codec	Raw	Gzip	Brotli q6
shorn	4,231,777	924,494	603,189
SchemaPack	4,331,777	937,975	597,776
Avro	4,344,802	935,333	632,034
msgpackr records	4,995,339	1,114,738	513,630
Protobuf.js	5,781,774	980,559	618,608
JSON	16,340,686	1,474,952	985,919

shorn is smallest raw and under gzip. It is not smallest under Brotli: msgpackr records are 17% smaller, and SchemaPack is slightly smaller. Brotli compresses their repeated metadata particularly well.

Compression CPU for the shorn payload: gzip 78.99 ms, gunzip 4.12 ms, Brotli q6 42.19 ms, unbrotli 5.25 ms. Brotli was smaller and faster here, which reverses below.

High-entropy data

Codec	Raw	Gzip	Brotli q6
shorn	6,987,333	2,337,080	2,084,918
SchemaPack	7,087,333	2,540,070	2,089,259
Avro	7,100,358	2,446,369	2,187,026
msgpackr records	7,750,895	2,598,288	2,235,235
Protobuf.js	8,487,330	2,508,528	1,943,144
JSON	18,996,242	3,001,786	2,580,139

shorn is smallest raw and under gzip, and second under Brotli. Compared with JSON, it is 63% smaller raw, 22% smaller under gzip, and 19% smaller under Brotli. Protobuf compresses best under Brotli in this fixture despite being 21% larger raw.

Compression CPU: gzip 111.90 ms, gunzip 8.29 ms, Brotli q6 163.15 ms, unbrotli 12.47 ms.

What not to claim

Do not claim that shorn is smallest under every compressor. Brotli can make msgpackr records or Protobuf smaller than shorn. The measured claim is narrower: shorn is smallest raw and under gzip in both 100,000-event profiles.

Cutting bytes further

Declare non-negative integers. ZigZag doubles the magnitude, so an int crosses every varint boundary at half the value.
Use enums, not free strings, for closed sets — one varint index against length plus content.
Prefer literals where a field is constant: zero bytes.
Choose a compact timestamp form. ISO-8601 is ~25 bytes, epoch millis 6–7. shorn will not choose for you — see rich types.
Ask whether every payload needs the fingerprint. It is 3 bytes: keep it for stored data; for pinned RPC, or when fingerprintHex rides in a header, the payload can stay bare.

Reproducing

pnpm bench          # small fixtures
pnpm bench:large    # 100,000 repetitive events
pnpm bench:entropy  # 100,000 high-entropy events
pnpm bench:all      # everything, plus correctness checks

Before quoting these results externally, regenerate every table with one bench:all run. Do not combine rows from different runs or machines.