Swift versus Rust

How the programs are written matters! Always look at the source code.

If the fastest programs are flagged * possible hand-written vector instructions or "unsafe" or naked ffi, does the host language matter? You might be more interested in the less optimised programs — more seconds, less gz source code.

fannkuch-redux
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* Rust #6	3.81	15.06	3,985	1260	11.92
Rust #4	6.94	27.12	3,985	1026	11.71
Rust #5	7.41	28.89	3,990	1023	11.79
* Swift #3	8.22	32.50—32.61	13,808	1103	14.41
Swift #8	34.68	34.68—34.78	13,476	470	12.23
Rust #2	9.19	36.04—36.08	3,723	1198	11.14
n-body
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* Rust #9	2.19	1.90—3.09	3,023	1881	11.01
* Rust #7	3.24	3.24	2,937	1759	10.53
Rust #3	3.46	3.46	2,937	1774	10.62
Rust #2	3.65	3.65	3,031	1809	10.49
* Rust #6	4.37	4.36—4.49	3,031	1796	10.86
* Rust #5	5.02	5.03	3,035	2224	10.61
Rust #4	5.13	4.99—5.53	3,039	1810	10.50
* Swift #3	5.46	5.45—5.53	25,002	1688	14.30
* Swift #4	5.49	5.49	25,010	1361	15.19
* Swift #5	5.52	5.50—5.55	25,010	1372	15.67
* Swift #7	5.53	5.52	25,010	1333	14.58
Rust	5.52	5.50—5.60	3,027	1483	10.84
Swift #6	5.81	5.79—5.86	12,947	1213	13.99
Swift #8	6.66	6.66	12,808	1285	12.73
Swift	7.89	7.88	12,808	1210	13.77
Swift #9	287.49	287.49—288.02	24,867	1532	14.21
spectral-norm
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* Rust #6	0.72	2.85	3,981	1132	12.60
Rust #4	0.72	2.85	4,047	823	12.00
* Rust #5	0.72	2.86	4,018	1062	11.30
* Rust #2	0.72	2.86	4,145	1117	11.00
* Rust	0.72	2.86	4,104	1262	11.75
* Rust #3	0.74	2.94	4,121	1060	10.92
Swift #8	5.36	5.35	24,936	411	15.00
Swift #3	1.45	5.71	13,705	607	13.91
* Rust #7		Empty
mandelbrot
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* Rust #4	0.95	3.78	35,598	1301	12.26
* Rust #6	1.08	4.21	36,426	1338	12.65
Rust #7	1.10	4.34	35,906	763	12.32
Rust #2	1.10	4.36—4.52	35,754	770	12.80
Rust #5	1.12	4.38	36,311	725	12.27
Rust #3	1.15	4.57	14,615	1013	12.66
* Swift #7	1.35	5.30	57,856	1147	15.57
* Swift #6	1.48	5.78	60,969	1147	15.74
Rust	2.01	7.90	42,631	874	10.94
Swift #8	25.63	25.62	12,841	426	13.44
Swift	26.55	26.54	12,853	400	13.78
Swift #5	7.28	27.12	49,291	665	14.09
* Swift #3		Bad Output
fasta
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* Rust #7	0.78	1.55	4,772	2533	11.68
Rust #3	2.03	2.03	3,199	1235	10.95
Rust #9	0.94	3.20—3.33	5,534	1952	11.24
Rust #2	0.95	3.46—3.50	5,554	1910	11.45
Rust #5	0.94	3.48—3.53	5,554	1963	12.19
Rust #4	3.52	3.53	128,217	944	10.63
Rust #6	3.53	3.53	128,381	959	10.62
* Swift #2	2.24	4.74—5.94	13,767	1952	15.21
Rust	4.45	4.54—4.61	3,113	1240	11.09
* Swift #3	2.20	5.37	39,313	2097	16.81
* Swift	5.43	5.42—5.47	12,640	1533	14.40
Swift #8	18.86	18.86—18.92	12,837	828	13.46
k-nucleotide
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
Rust #7	2.57	8.13—8.39	139,088	1585	13.43
Rust #3	3.28	9.72—10.13	142,631	1549	11.91
Rust #6	2.79	10.06—10.15	165,048	1697	14.10
Rust #5	3.88	11.66—11.92	143,155	1745	12.40
Rust #2	6.00	15.71—16.24	142,946	1350	11.85
Rust #9	6.33	17.72—18.82	141,099	1850	14.41
Rust #4	6.69	18.00—18.74	142,090	1755	13.13
* Swift #2	14.46	55.16—55.44	273,932	1373	14.99
Rust	21.08	64.42—65.12	161,219	1086	12.16
Swift #8	167.99	175.66—188.61	904,810	658	14.96
Swift #7	225.53	231.92—242.63	649,970	607	14.99
Swift		Empty
reverse-complement
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* Rust	0.55	0.85	512,963	2762	11.72
Rust #2	1.01	1.61	1,022,128	1332	11.04
Rust #3	1.02	1.72	1,022,034	1105	11.45
* Swift	1.97	2.41	825,594	1293	16.00
binary-trees [ Contentious. Different approaches. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
Rust #5	1.07	3.84—4.01	139,121	771	1.28
Rust #2	1.17	4.16—4.25	140,157	729	12.50
Rust #4	1.38	4.98—5.02	202,686	765	12.32
Rust #3	1.40	5.15—5.26	172,392	762	11.90
Rust	2.10	7.44	137,417	760	11.36
Swift	18.32	54.27—54.38	763,609	720	15.54
Swift #4	17.69	55.61—57.68	733,131	772	15.64
Swift #5	18.99	56.13—58.05	764,781	813	14.50
Swift #2	18.36	58.30—64.86	733,131	822	15.77
Swift #3	18.24	58.63—59.13	733,000	868	14.57
* Swift #9		Empty
pidigits [ Contentious. Different libraries. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
Rust #4	0.71	0.72	4,055	804	11.82
* Rust #2	0.75	0.75	4,387	1312	10.44
* Rust	0.75	0.75	4,243	1426	10.19
* Rust #3	0.75	0.75	4,510	1373	10.10
* Swift #2	0.76	0.75	14,238	606	13.58
regex-redux [ Contentious. Different libraries. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
Rust #6	1.21	1.46	159,846	994	13.12
Rust #5	1.35	1.58	209,863	777	12.67
Rust	1.35	1.59—1.63	159,793	811	12.22
Rust #3	1.38	1.63	210,379	726	13.51
Rust #4	1.38	1.64	206,811	771	12.41
Rust #2	1.38	1.64	159,937	707	11.67
* Rust #7	0.78	2.00	157,442	2464	12.48
Swift #2	38.81	38.84—39.05	710,750	678	14.74
Swift	23.39	39.78—39.91	922,284	721	13.23
Swift #4	18.22	41.22—41.58	1,099,583	751	14.65
Swift	Swift version 6.0 (swift-6.0-RELEASE) Target: x86_64-unknown-linux-gnu
Rust	1.84.1 (e71f9a9a9 2025-01-27) LLVM version: 19.1.5