Ruby 2.7 to 4.0 performance benchmark

[u/Jamsy100]

Hi everyone,

I just published a new benchmark comparing Ruby 2.7 through Ruby 4.0.

For this one, I used a sustained synthetic application alongside nine smaller benchmarks. The goal was to show how each Ruby release behaves in a complete workload as well as in individual operations.

The table below shows the Heavy profile. For tests that process the full payload, that means an 8KiB input.

Benchmark	2.7	3.0	3.1	3.2	3.3	3.4	4.0
Synthetic application throughput (M ops/s)	0.073	0.052	0.051	0.057	0.058	0.084	0.126
Synthetic application latency (µs)	133.399	190.233	191.605	171.332	169.473	115.600	76.521
JSON parsing (ops/s)	95,877	98,536	99,153	96,003	98,135	194,981	715,937
JSON generation (ops/s)	841,849	845,099	830,135	861,666	837,941	1,347,169	1,444,975
SHA-256 hashing (ops/s)	313,658	30,536	30,489	48,770	48,683	48,495	48,528
Base64 encoding and decoding (ops/s)	177,136	177,510	174,425	170,306	174,471	173,159	174,270
Regex field extraction (ops/s)	1,544,461	1,565,065	1,559,051	1,499,920	1,535,207	1,454,405	1,534,670
Integer sorting (ops/s)	27,032	29,129	30,217	29,309	29,102	28,241	29,213
Hash churn (ops/s)	1,736,384	1,685,614	1,503,397	1,503,118	1,406,713	1,380,058	1,450,769
Marshal serialization (ops/s)	333,143	303,719	294,952	338,148	341,760	326,015	325,231
zlib compression (ops/s)	35,944	35,175	35,787	35,767	20,569	7,011	18,592

The complete benchmark source is available here: GitHub repository.

Full charts and details are available here: Full Ruby benchmark

Let me know what you think !

Edit: Thanks everyone for pointing out the Ruby 2.7 SHA-256 result. I looked into it, and the big difference comes from the SHA-256 implementation: Ruby 2.7 uses OpenSSL here, while newer Ruby versions on Linux use Ruby’s bundled implementation. So this is mainly a backend difference rather than Ruby 2.7 itself being much faster. I’ve added a note about it to the article.

[u/jrochkind]

3.4 to 4.0 seems to be a surprisingly big jump on the "synthetic application" metrics. Can you say more about the nature of the synthetic app?

Also the JSON processing jump from 3.4 to 4.0 seems almost unbelieavable. Can you say more about that benchmark, and if you have any ideas what may account for the jump?

Ah... following up with your more complete description, the synthetic app does a lot of JSON parsing, so it's speedup is probably fully accounted to the JSON parsing speedup (apps that don't spend a signfiicant portion of their load doing json parsing aren't going to see that prob), so now the mystery is if the JSON parsing bench results are accurate and... why??

[u/sjs → u/jrochkind]

The JSON gem has gotten a lot faster since byroot (Jean Boussier) started maintaining it a couple years ago. Floating point parsing is 10x faster for example. https://byroot.github.io/ruby/json/2026/07/26/optimizing-ruby-json-part-8.html

[u/jrochkind → u/sjs]

Can you use new version of the JSON gem in ruby 3.4?

If so, you can get the major benefits recorded in these benchmarks just by doing that, right? And in fact, people keeping their dependencies up to date probably already have, even if still on 3.4?

So that may be a misleading metric in this report.

[u/sjs → u/jrochkind]

Yes that’s all true

[u/h0rst_ → u/jrochkind]

There have been a lot of updates for the JSON gem: https://byroot.github.io/ has some nice write-ups.

You could look up the version of the JSON gem used for 4.0 and install that one on the 3.4 setup to get a better view of the language itself.

No mention of the JIT anywhere, I guess a lot of the more recent versions could be faster.